I have it and use it occasionally. People are not huge fans of it other than the UI, because it's pretty bare bones feature-wise. They've also been teasing a big update for the past 2/3 months but no news since.
This is a great Twitter app! I was a little weary of paying $7 for it, but now that I have it, glad I did. Bravo TweetGenius!
You must not have used Ubertwitter before, which is free. TweetGenius has a great UI but the features are extremely limited when compared to Ubertwitter and at $7, it's a very tough sale.
I had tweetgenius, but I didnt have to pay for it, I won it in a crackberry contest, overall very good app I like it a lot, BUT I just got my Socialscope invite yesterday and I havent looked back! If I were to use a free app it would be ubertwitter though. Couldnt see myself actually shelling out $7 for a twitter application