Think shadows and the UI are the two biggest ones on the PC
i really really hope they fix the PC shadows - i've tweaked and tweaked and while they're still annoying, everything's "livable" except for my house... inside everywhere else it's blocky, but inside my house i have horrible moire-type shadows over everything, and even those are pixelated!

and i think i've spent as much time changing .ini values as i have playing...
i haven't noticed broken quests (yet), but those are pretty darned inexcusable. and the PC UI would benefit from a ton of work that should have been done BEFORE release. for one thing, i would like to be able to activate say, a cooking pot without a pixel hunt. it's not that small. /sigh
kinda makes me miss the old days when patching was impossible/difficult, so software was (mostly) finished on release. as a consumer, i don't have a lot of patience with the "oh, we'll just fix (aka finish) it in a patch" attitude. and i find PR veep pete hines' "http://www.computerandvideogames.com/326186/skyrim-patch-inbound-for-all-platforms/." comment very patronizing and un-empathetic. gee, now it's OUR fault we want to enjoy a game rather than being frustrated by its faults and broken pieces? thanks for caring, gamesas.