I like DoubleTwist because "it just works". It's designed to be utilitarian and it will sync with any device - something that iTunes obviously does not. As far as just a media manager on Android - all I can say is hold on, there are several good products for that in the pipeline other than what will be in Gingerbread (Android 3.0).
I haven't used the Kindle app, since I don't have any Amazon e-books, but I've read the same thing in other reviews. Also, from experience, the Audible app for Android is also more polished than the one for iPhone, and it's still technically a beta. I plan to test out the Nook software more thoroughly in the coming weeks since my wife has a Nook and a library of books I can use for it.
The compass on my Droid works fine, so I'm not sure why it wouldn't work properly on your phone. Maybe it's a 'design feature' and you're just holding it wrong? Is it a built in app or are you using the 3rd party compass application from the marketplace?
The 'new' Android marketplace will make it much easier to find the more 'polished' applications in the near future, along with many other areas of integrations. Froyo does take a nice step in that direction, but Gingerbread is going to be the 'biggie' in terms of polish and integrations.
Once I have my hands on the new Samsung, I will decide if I'm going to pull the trigger on ordering a Droid X or hold off a tad longer for the Galaxy line.