TweetDeck

Very attractive interface and good functionality. Recent updates fixed many previous problems.

Works fine for me, but I haven't tried the other Twitter apps, like the one Mag mentioned. Perhaps I'll download that one and try it out.

I use TweetDeck on my iPhone and Seesmic Desktop on my Desktop. TweetDeck is a good tool to see updates from your twitter friends from different accounts (they improved this part because when I first got it, it didn't support different account). It's quite good from the publishing point of view. It's easy to post your tweets, reply, send direct messages, include pictures, location... What I don't like about the app is that I can't search for keywords or trends from the app. I think real time search is the most important advance that Twitter offers and there is no way to take advantage of it with TweetDeck.

It's not as good as m.twitter.com. Sure, there's more functionality, but all too often, the API is broken, and the content is not updating (I know this isn't Tweetdeck's fault). The three column layout is a good idea in theory, but in practice, I like m.twitter's look and feel better. Maybe I'm just old school.