In cities, I'm constantly reminded of the limitations of the game by the endlessly repeated one-liners by the same people as I walk past them. At least removing the individual lines ("You know what's wrong with Skyrim? Everyone's obsessed with saying the same thing over and over again!") would make them say 12 different generic things that all NPCs say.
Yes. For all the talk of "70 voice actors!", voices are repeated everywhere still. I've never really been one to complain about that, but some of Skyrim's voices are worse than Oblivion (hint to Farengar: "voice acting" is acting of the voice, not the act of voicing; and if I hear Arnie one more time...). Not only that, but it's now even harder to tell certain races apart (there's little visual difference between Nords and Imperials, and I swear I heard the same voice among some Nord and Imperial NPCs; sometimes the difference between Nords and Bretons aren't all that clear cut, either). Making sure there's no cross-pollination of voices between races, allowing the majority of non-hostile NPCs access to more of the generic lines that already exist, and allowing them to partake in Radiant Story quests that already exist, would have gone a long way for little effort.
I also don't really like what happened to the beast race voices. You go back to Redguard and Morrowind, and they sounded decidedly not human. Khajiit had cat-like inflections in their voice (purring, etc), and Argonians had "lizard"-like inflections (hissing, etc). Now, Argonian voices could easily be given to humans without sounding too out of place, and Khajiit just sound like humans with laryngitis that have some difficulty saying "I" or "me". That said, I don't really dislike the voices (very sad to not hear Jonathan Bryce doing any of them, but the new Argonian voice is pretty good and the new Khajiit voice is decent), I just wish they worked more on fitting them with their non-human nature.
Now, however, with Skyrim, I'm somewhat disappointed that you have only two real climates - brown river valleys and snowy mountains.
I'm not sure I'd agree with that, though. The plains of Whiterun, the forests of Riften, the canyons and (exquisite) plateaus of The Reach, the swamps near Morthal/Solitude, the snow plains by Dawnstar, and the cliffs of Winterhold, are probably more distinct than Oblivion's regions (not that Oblivion's weren't, just saying).
The biggest problem I find is the weather system. Go up a snow-capped mountain and it's almost guaranteed to turn into a blizzard, which doesn't help in uniquely identifying them. Why aren't there naturally-occuring downpours or severe thunderstorms? Where's the light snow? Thundersnow? Light fog? Not sticking to the same limited weather patterns for similar areas would help in making them less generic.