For power users, it clearly saves time in some circumstances. It also jumps around alot and does things that are very different than before. One person said it is like a guy who finishes your sentences, "More annoying than helpful".
What's the verdict?
I'm the guy who did all the prototyping on Google Instant, and I attended >90% of the user studies we conducted at Google. (and I'm going to try not to be biased!)
We went through several iterations of prototypes based on our internal testing. What we found worked really well with the current implementation was that study participants either (1) saw the results while they were typing, and proceeded to click what they wanted, or (2) never noticed anything changing because they were hunting-and-pecking on the keyboard, or else too busy looking at the suggestions. That validated our goal that it wouldn't be too distracting. Of course, when a large part of the page changes like it does in Instant, users can't help noticing the change; the important thing is it shouldn't interfere with their task.
Yes, it might feel for certain queries that Google is thinking for you, and auto-completing things for you. Though, this happens much less frequently than you'd think, but you end up remembering more vividly. All the other times when you saved time by not having to type an entire query, or because Google suggested a better query than what you were intending to type, or because you saw a quick preview of the results and decided to refine your query further — all those instances get forgotten more easily because you expect Google to work that way. Try keeping track of all the instances where it worked well for you, then compare against the number of times it felt odd to you.
One of our participants said: “It found a way of asking the question that I hadn't even considered.” (verbatim, from study transcript.) Google Instant helps a lot of users formulate their query better. Many of us here cannot imagine query formulation being a huge problem, but it is. Instant tries to make that just a little better.
We also minimize the amount of flickering on screen when results change. Given the realities of network latency in shipping a new set of results from the server to the client, we have a lot of black magic going on in the interface that attempts to minimize the visual noise when results transition. For example, when new results are available, the old ones fade out quickly through a transition to grey; this was noted as a strong indicator by our users that "Google is thinking"; without it, users didn't realize that results were different, unless there was a huge map or a huge picture in the middle of the new results page.
Here's a longer description of the user studies we conducted.
Good UX because they asked a lot more people than you did. :-) There's a great write-up on Google's blog.
We knew it would take extensive testing to find the right design, so we ran through a sequence of prototypes, usability studies (testing with people from the community), dogfooding (testing with Google employees) and search experiments (testing with a small percentage of Google users).
…
In user studies, people quickly found a new way to interact with Google: type until the gray text matches your intention and then move your eyes to the results. We were actually surprised at how well this worked—most people in our studies didn’t even notice that anything had changed. Google was just faster.
Can't stand the thing.
It's too slow It can sometimes take a good few seconds for the page to update. When it does, you've continued to type, but you have just seen the gem of a result.. but oh no, it's now rebuilding the list again based of the latest garble of text you've entered - and your gem is buried in the haystack once more
It's very distracting There was a study done about how big changes in what you're looking actually clears your short term memory. I can't remember the exact name of the study, but it certainly rings true on Google's instant search. I've quite often seen something appear in the instant search that looked really interesting, but wasn't really what I was looking for... and then I've had to stop and remember exactly what I was typing. Maybe not so bad if you're searching for small terms, but larger term searching is actually harder now IMO.
It's ugly The rapid updating and the bouncing all over the place is just plain ugly IMO.
The only good thing about it is that to turn it off, you don't have to find the option in your user account settings - it's right there next to the search bar. (IMHO of course :) )
Edit
To help fortify my answer and alter it from being 100% subjective to being at least slightly objective, here are a few links to reviews on Google Instant, which have comments by users/readers who mostly share the sentiments of the article:
http://www.google.com/support/forum/p/Web+Search/thread?tid=1f475d87e142c7a8&hl=en
http://www.google.com/support/forum/p/Web+Search/thread?tid=49ef1e2a99799751&hl=en
http://www.zdnet.co.uk/blogs/jacks-blog-10017212/google-instant-or-google-stupid-10018659/
http://www.product-reviews.net/2010/09/09/google-instant-search-consumer-feedback-after-update/
From my own research, it seems there are more people publicly stating their dislike, than those stating their liking. Obviously, this is almost always the case, but without running your own independent testing, I don't know how you could answer this question any more objectively :)
I don't like their implementation of instant results.
I love filtering results when the list is a regular font size and can only become more exact with the more text provided to the filter itself. (e.g. taking a list of 300 items and after 6 letters showing only 4 results.)
My major beef with Google's implementation is:
As it stands now, I have instant search turned off. I'll test it every now and then but I was having a better time with the regular "enter the query and press enter" approach.
It's good UX. That its implementation leaves something to besired (like lack of speed,although I haven't experienced it), does not change that the principle is sound: the only logical next step after entering a search query is to actually perform the search, so you might as well just skip that step and do it for the user. Also, it's not finishing your sentences, it's providing shorter and thus faster paths to your desired search results.
Google instant is bad UI. There is inconsistent indication it is working, therefore I never know if what is shown on-screen is for what is currently in the text box, or what was previously in the text box. I find I have to impulsively click the "Search" button when I am done to make sure what I am seeing is for what I have finished typing. In other words, through usage I have found it unreliable, so I inherently distrust that it is correct. Because of that, it slows me down by making me think, "is it working?".
A sign of good UI is that a user does not have to think to use a piece of software, they just flow with it. If the user has to constantly evaluate what is going on, you have lost.
Don't get me wrong, I love the instant feedback, but I think "google suggestions" is a better approach.
Let me give you another example of bad google UI: the Bookmarks list in the default android browser. This list always moves frequently used items to the top of the list. This may sound "helpful" in theory, but in practice since the locations of bookmarks are constantly changing, what it does is remove any ability for me to memorize the location of the bookmarks in the list. When I am sitting at a traffic light and want to check the weather, I cannot simply pop open my favorites and go to the weather link from muscle memory. I have to actively scan the list. There is a reason Microsoft removed this feature from Office menus.
Rule: never change or move UI elements on the screen.
Rule: Don't make the user think. If they have to actively evaluate your user interface every time they use your software you have lost.
I really like it. It seems a little slow at first, but I believe over the next few days, they'll iron out that and it'll be fantastic :) I find it much more useful for when I'm looking for complicated searches, like looking up a specific coding errors etc.
I've actually just asked a question on a similar vein to this, as my company are looking at adding this style of dynamic search to our software products.
Google instance come to change the user interface with the user on the common search dialog.
This is not so good for the moment because google is the only one that done this and I do not think that other software can do this for the moment.
So the google search has a different user interface that make all of us to confuse.
I think it is a great UX idea. It allows advanced users to instantly refine search terms to see get the best results while less advanced users can probably find what they're looking for after typing three or four letters.
Great idea, and it will only become better as Google remembers common searches for logged-in users and displays results after only one or two letters.
I know they try to maintain their original home screen (logo, search box and button in the middle), but I'd rather not have everything jump to the upper-left after typing the first letter. If Instant is on, just start there to begin with. It's not like it would be that hard to find.
I will say, if you're having trouble spelling one of your search words (could be the reason for doing the search in the first place), the immediate response is very beneficial.
I type faster than it can provide feedback, so it over-writes my correct answers with wrong ones.
Hate it.
As I have gotten used to it I actually think it's pretty good.
Extremely efficient in most cases. I can only see it getting better as it gets "smarter" from use and trends. Has done far more good than harm for me so far.
FWLIW, I don't pay any attention to it. I just type like I always did and, occasionally, use the autocompletion aspect of the search bar. The only time I notice the listing of results is after I finish the query text. This probably has allot to do with the fact that I can't type well so I generally look at the keyboard when typing. That, and I'm an old phart who started his computer interfacing on TTY's.
Love it, it helps me think of better ways of phrasing things. It also provides humorous and off the wall suggestions sometimes which help to give me a chuckle. Way to go Google.
