I’m also pretty happy about the fact that it runs fine on Fedora too.
In fact, as far as “packaging” goes, the .rpm and .deb files simply consist of small bootstrappers that download/execute Steam in ~/.local/share/Steam (not too dissimilar to the way it works in OS X, where all the meat goes in ~/Library/Application Support/Steam), which makes it remarkably easy to repackage it for another distro.
Rather than rely on the distro’s package managment for updates, instead they’re using Steam’s own auto-update mechanisms to keep both Steam and the games up-to-date — the same as it works on Windows and OS X.
Though perhaps this is not the most “pure” approach, I guess it is the one that makes most sense coming at it from a cross-platform standpoint.
So far the main bugs I’ve run into are crashing when Alt+Tabbing in Counter-Strike: Source, unendurable loading times in Team Fortress 2, and the fact that keystrokes don’t get registered within Steam Community In-game.
Oh, and the Steam interface is still as clunky and horrible as it is on Windows and OS X, but apparently that’s a feature. :-)
+1 for the horrible loading times for Team Fortress 2. It's certainly not CPU or disk IO bound, so I have no idea why it's taking so long to start up.
I think they've done a pretty good job at mixing bundled libraries and relying upon system provided ones. For example, if you install something like Bastion, it goes and installs Mono in the background. I also occasionally see it force an apt-get update for certain packages.