82 hours into Skyrim after about a week, and here's what I think ought to be changed:
Dungeons are brilliant, when they work. When they don't work, you feel like you're just running around killing Draugr. Some more diversity in both dungeon enemies and planning is needed here - spiders were fun to fight for instance, but there aren't enough of them.
Some of the puzzles in the dungeons are bloody brilliant - but they lack diversity. There's essentially two puzzles in Skyim: the dragon claw ring and the symbol match, and while Bethesda found a whole lotta ways to keep the second one interesting, the first gets old after the third time you do it.
Traps don't feel lethal unless you're criminally stupid and stand in their way. Hell, half of them can be beat just by running really fast - this isn't a good trap at all. And the lack of unique triggers means that 90% of the time you won't even trigger the trap, because noticing those tripwires and floor panels is incredibly easy. Traps could also use more diversity - the first time you see a slashing axe trap you're like HELL YEAH, but after the fifth you're like "Is this the only kind of trap these guys know about?"
Dragons feel stupid and they are too frequently spawned when you fast-travel. Either they get stupid and attack other enemies, allowing you to freely kill them, or they trot up to you and 1-hit kill you by nom-nomming your head off, which isn't conducive to having fun. And if you fast-travel a lot, dragons wind up becoming more of a travel tax than an interesting encounter - it doesn't feel random when, after fast-traveling to three open areas, I get attacked by three dragons in a row. I have more dragon souls than I know what to do with at this point. And they lack diverse attacks - it's either bite, breath, or tail slam, with the odd overhead breath attack.
The inventory is a gods-awful mess, especially the Misc and Potion categories. I understand there's a mod that fixes it, but I'm playing the vanilla game right now and will critique it as such.
Some perk trees are absolutely pointless. Speech and Pickpocket are both pointless: the former because you just don't need it, the latter because it's mostly a tree for RP'ing as a thief. The Lockpicking tree is also worthless unless you suck at the lockpick minigame.
Taking Enchanting is an insane priority over Smithing and Alchemy, since you can just enchant with "fortify alchemy/bsmithing" and then BOOM you level those skills a bajillion times faster.
Magic seems poorly implemented: sure Destruction's fun to use, but Fire seems to be the dominant element, with a bit of lightning mixed in to take out mages since nobody ever has ANY elemental resists whatsoever. Frost magic seems pointless other than for making enemies a bit slower. Alteration and Illusion get fucked over in favor of Conjuration, Restoration, and Destruction - sure, invisibility and muffle are cool, but there isn't anything else worthwhile in Illusion, and Alteration's sole virtue appears to be Oakflesh.
Hitting birds with anything other than lighting bolts to get their ingredients is hard as hell. Realistic to be sure, but annoying in game terms.
The whole "conquer Skyrim for either the resistance/Legion" is a cool idea, but the whole "battle for Fort Whatthefuck" minigame attached to it is dull as hell. How about mixing it up a bit, eh? And let's see some actual CHANGES when you take the areas other than the Jarls moving out - some new quests would be nice. And I shouldn't have to be re-Thaned each time I take over an area. And the Thane-dubbings should have more unique dialog.
It really doesn't make sense for me to be able to trot into the enemy capital when I'm supposed to be a figurehead of my movement - swaggering around Solitude when I'm going to be taking it over in an hour (and all the Jarls in the basement hate me, and probably told the Jarl of Solitude who I am) strikes me as being more than a tad silly. I'd also like to be able to actually, you know, have INPUT on the whole Jarl situation. Some of those people I wanted to keep. And what's with the racism coming from people I'm supposed to be a hero to, anyway? And why wasn't all of this tied into the main quest line - it's kind of goddamn important!
Why does the Dark Brotherhood's big quest not DO anything? Someone important just died: there should be more than two line's worth of dialog changed here!
Once you hit the 30's the difficulty of the game just disappears, at least at the "Adept" setting. Only thing that threatens me now is dragons, and even then it's mostly because of the stupid 1-hit kill move.
The houses outside of Morthal suck donkey balls in terms of aesthetics (though I haven't gotten the one in Solitude yet, so I still have hope). Breezeholm is a shitty house for early game, I get it, but couldn't I make it nicer given the money I put into it? And isn't the one I got in Ulfric's city kind of, well, empty? There's room for entire dining tables in here, even with the upgrades! What's the deal?
Of course, all of this ignores that I had a lot of fun with Skyrim. But I could have had EVEN MORE with this stuff fixed.