Kijamii, by The Jared Company, is possibly the simplest, cleanest Twitter app I've ever seen. Some have said it's a little too simple or boring and while I can't exactly disagree, I do believe this app has great potential for a target audience that simply wants a basic Twitter app.
Kijamii may have a simple look but it does have every main function of Twitter (including one that a lot of us on Twitter for BlackBerry would love to have), the ability to see which of your tweets has been retweeted. I personally enjoyed my time using Kijamii thanks to the simpleness of it, lack of ads, and overall fast response
Cons: Lack of push made mentions come in very late (same as my biggest complaint with SocialScope). Also, Since there are a lot of options to choose from, and no tabs, it does take longer than I would personally like to go between Mentions/Tweets/Timeline/My Profile.