I've put a solid 4-5 hours in so far, and I gotta say I love it. I tried getting in to Oblivion like 5 or 6 times over the last few years and I never could get far before the boredom forced me to put it down.
The graphics look great to me (though admittedly I haven't played many recent PC games with really good graphics, like Witcher 2, Crysis, etc), the combat is fun, the skill/level system looks really well done, the voice acting is passable to good, and best of all there seems to be a huge mountain of content available. I have yet to try the magic system, but that may have to wait for a separate play through as I'm really enjoying my hybrid stealth/bow/1h+shield build that I have going at the moment. I am running everything at ultra settings with great fps, and I have not run in to a single bug, glitch, or crash yet. The only strange thing is that when I alt-tab out of the game, the only way I can get back in is to click the Skyrim icon in the task bar which brings up a black screen, then I have to alt-tab and just click in the blackness and the game will come back up. I've done it at least a dozen times and its never caused a problem so I'm not worried about it just yet.
I really dont understand the complaints about the UI. Everything you need to do can be done easily with the mouse or with pre-assigned hotkeys (and most actions can be performed with whichever one you prefer), and all of the menus are simple, logical, and easy to understand. I will admit that the first few times I tried to loot a container I became incredibly frustrated because I couldn't figure out how to close the damn thing, but once I realized you can close pretty much ANYTHING (menu's, containers, books, dialogues, inventory, crafting menu's, shops, etc) with the Tab key (conveniently located right next to your WASD keys), I have been cruising along with no issues.