I forked over $10 for this, but am badly disappointed. I might stick with it because it (1) doesnt have ads (as far as Ive seen so far), (2) allows saving draftts, and (3) allows managing lists (though in a very slow and tedious way). But it has many problems. Ill mention a couple of them here.
First, it appears to give you a background app that lives in the menu, but that is deceptive. As soon as you close Tweetbox, the menulet goes away. This means your "Global New Tweet Key" and your "Global Show/Hide Key" are not really global. They only work when the app is open, which makes them nearly useless. Switching to an open app is quick & easy, so this doesnt really save me any time. I want a way to Tweet without having to open an app or keep it open all the time. A menu thats only there when the main app is open is similarly nearly useless. The menu should belong to a background app that doesnt appear in the application switcher menu (or the Dock, for people who still use that).
Secondly, a lot about the UI is unclear. For example, theres a checkbox with nothing more than the label "Streaming". Huh? I could experiment to figure out what it does, but why dont they have explanatory text or at least a tooltip? The only thing I can guess is that it means tweets come in without you needing to refresh, but why would anyone want to turn that off? Why would you ever want to have to refresh? Maybe theres a reason, but a complete sentence for the label would be helpful. For another example, I had to hunt around a lot to find how to block someone, and oddly theres a single button in a weird place for both blocking and reporting spam. Weird.
Replies dont show up in your timeline. Huh? You have to go to "Mentions" to see them. That seems very odd.
Adding users to lists, as I mentioned, is a very slow process if youre adding more than one or two people to the list. This could be made dramatically easier with a little thought.
There were a lot more oddities and frustrations I ran into when I first tried it, but these are the ones I can remember. It might be the best option out there in some ways, but the UI needs a lot of work.
mister zed about Tweetbot for Twitter