I like iTunes, and use it primarily for anything audio. (Audiobooks as well as music.)
I have an iPod which is why I got it in the first place, but I don't resent switching. I like its search feature, Sound Check (great for headphones), and the interface in general.
I don't get the video feature, mainly b/c I hate the iTunes store and refuse to buy any videos formatted for it. Plus VLC and even WMP are much better at handling videos than iTunes/Quicktime (I hate that you have to get the pay version to get fullscreen playback in Quicktime. Lame.)
I agree that iTunes is slow to start and the integration of the Store, whether you want it or not, is beyond annoying. But I'm willing to live with it for the usability otherwise.
On the video end, I like VLC for its awesome ability to play just about anything, but I wind up using WMP primarily since it's the default application and I don't care enough to switch it.