Excellent question ! Apparently a study by globalwebindex shows that after the launch of reactions, the number of users who interact or react with a post has increased after Facebook introducted Reactions. To quote the article
The replacement of the one-size-fits-all button appears to have been a
hit among Facebook’s users. GlobalWebIndex’s data shows a clear
upswing in the number of Facebookers “liking” things on the platform
since the new button was launched. It’s now a sizable 8 in 10 who are
clicking “like” or "reacting" to posts each month – a 16-point jump on
the previous quarter.
With regards to your question on whether users spend more time deciding on which reaction to use, I still am yet to find data on that but one impact might be on how people interact with positive and negative news.
A study from facebook found that when people posted positive news they got a lot of likes but when they posted negative news, the number of comments were significantly higher. To quote the article
We categorized the top 200 feelings as positive or negative, and
whether they related to the poster's self-worth (e.g., feeling
accomplished, feeling proud, feeling defeated, feeling stupid all
relate to self-worth, while feeling lucky, feeling rested, feeling
tired, and feeling furious don't). Ambiguous or neutral feelings (like
feeling weird, feeling crazy, feeling hungry) were omitted from
analysis (about 11% of feelings). See the paper for the full list of
feelings. Roughly 1/3 of feelings shared on Facebook are negative,
indicating that people share more than just good news on the site.
Then we counted how many likes and comments these posts received. Not
surprisingly, posts with positive feelings (like feeling excited) get
about 58% more likes, and positive self-worth feelings (like feeling
strong) get about 71% more likes. Our analyses control for other
factors likely to affect the use of feelings and feedback rates, such
as posters' age, gender, friend count, and years using Facebook.
But when people share difficult moments, their friends skip the like
button and instead write comments. Posts with negative feelings (like
feeling upset) get 36% more comments, and negative self-worth feelings
(like feeling lonely) get 72% more comments. Figure 1 shows these
Figure 1. Posts with positive feeling annotations, especially those related to self-worth (like feeling loved) receive far more likes than
posts without feeling annotations. On the other hand, posts with
negative feeling annotations, especially those related to self-worth
(like feeling hopeless) receive far more comments and far fewer likes.
Error bars are doubled for visibility.
Hence with the new reactions,since users earlier did not have an option to communicate displeasure and had to use comments, it would be interesting to see how the impact on comments is there when negative news is posted.
Also this article which checked people's reactions to posts on popular facebook pages shows that LIKES still leads the pack. To summarize the article
- Like is used 92.9% of the time
- Love is used 4.6% of the time
- HaHa is used 0.3% of the time
- Wow is used 1.8% of the time
- Sad is used 0.2% of the time
- Angry is used 0.2% of the time