I purchased it but deleted it from my iPhone after a few days.
The main reason is that there is just too much bright white, which I don't find pleasant for my eyes. I also don't like the round avatars.
For now I am using the old version of Tweetbot and also Tweetlogix. A dark theme is promised for an update of Tweetbot 3, I will try the app again then.
By the way, take a look at Tweetlogix in the appstore, this app has a really nice iOS 7 design, beautiful.