Currently developing a WPF application with a completely customised UI. Just wondering if anyone has any tips to allow the UI to be unique, but still look professional and polished.
Consistency is a big pointer to something being professional and polished.
- Make sure all your icons are a the same size and properly lined up.
- Use a consistent font and text size throughout.
- Make sure that if there are options to change font sizes that they affect all text items.
- Make sure that changing the colour scheme affects all items consistently.
I know it doesn't make your application unique, but the UI is the first thing your users see and what they have to interact with every time they use it.
As a rule of thumb, professional means clean and simple.
Regarding Animation - it really depends on the application. Animation often implies applications that are more casual, so it would work great for games or consumer applications. If we're talking about enterprise software, it might not be appropriate.
I think http://soluto.com/ is a great desktop application to use as a reference. You can download if for free and install on any PC.
As has already been pointed out, consistency is important - not just in terms of appearance, but in terms of behaviour.
There are times though, when deliberate breaking of consistency is not just a good idea, but necessary.
Part of achieving a "Professional and Polished" look is knowing when to do this.
On StackExchange sites, the "Ask a Question" link at the top of every screen isn't apart of the sequence of other buttons - it's right aligned, giving some visual isolation.
In Microsoft Outlook 2007, the Send button isn't included in the Ribbon along with everything else, it's kept separate and always accessible.
Study, study, study.
Observe the competition or similar products.
One of the best things about UI is that you don't, and IMHO shouldn't, reinvent things. I know your question involves a desktop application, but even still a run through Google Images (based on appropriate keywords) ought to serve up many, many examples of how your general situation has been designed to date.
And by all means, TEST your UI on candidate users. It's remarkable how few DEVs take the time to do this and the returns are typically very valuable.