Goodby, OS X
The biggest plus so far has been the ability to simply copy things off of my iPod and into my music library just by dragging them. This is something that iTunes was designed to prevent you from doing. Rhythmbox just does what you'd expect. So, it has finally happened; Rhythmbox is now better than iTunes.
Not that this has very much to do with Rhythmbox, mind you. It's just that Apple's latest iTunes, released into the world in much the same way as a turd, is so magnificently hideous that I can hardly stand looking at it. Not only is it a turd floating in the swimming pool of great Apple applications, but it actively prevents me from doing simple, obvious and useful things. Keep my music files on the hard drive of a computer with a 1000base-T connection directly to MAE-WEST? No problem! Allow me to move my files from one computer to another by hand-carrying them on my aged iPod? No, that would promote piracy!
And then, there was the issue with my iPod Shuffle. iTunes has this thing where it sort of gloms onto your Shuffle, urinates all over its poor little filesystem, and tells all the other Macs that might encounter it that, "This is my Shuffle! You can't put any music here!" So, my sister copied some of her new music (yes, actually hers, as in she is the artist) onto my Shuffle. Her iTunes claimed my Shuffle. When I want to put any other music on it, it will insist on deleting everything she put on there. I can't copy her music into my library, because that would be naughty.
There are an assortment of tools and tricks that one can use to defeat these "features" of iTunes, but that just seems stupid. Anything that requires a work-around is, in my opinion, a bug. So, despite crashing all the time, Rhythmbox actually has fewer serious usability bugs than iTunes.
My only compliant for Ubuntu is that they need to detect the right modules to load to keep Apple's Gigantic Fans of Doom from levitating the computer from my desk. Evidently, loading the very well named windfarm_cpufreq_clamp makes everything happy.
Other than that, my only complaint goes to Apple for putting a crappy nVidia chip in this thing, and to nVidia, for their stupid closed-source drivers.