My only problem so far with the game (aside from some bugs, but that's to be expected) is when they have some characters/fights who are simply overpowered in a cheap way.
Other than Destruction sucking balls in this game (More and more people are finally starting to wake up where as before they would say stupid shit about how strong "stunlocking" Mages are and that there's nothing wrong and that people just aren't smart enough to play a Mage...), I have major issues with the way the game scales certain enemies as well.
It's not that they become impossible, it's just that it's completely illogical. I am playing on Expert right now with a new character, and right at the start you get a "Go kill the bandit leader" quest. At level 7 I go there, smash everyone up to the boss, but guess what? He has a two-hander that can kill you in a single power attack and health that is probably four or five times that of the next toughest enemy. I would not have an issue with this if players could do anything remotely close to how they have the NPCs behave. I don't know if this is actually intentional, or if the perks and combat just don't function correctly for the player. Try using a two-handed weapon. They suck ass. They are ultra slow and if you do a power attack, watch out...because you're going to have follow through with it and you're totally open for a few seconds to whatever the enemy wants to do EVEN IF YOU HIT THEM. Yet NPCs never have this problem and seem to swing 3x faster than what you can with the same weapon.
Enemy Mages also actually hit for 4x - 6x the damage that you can do with the same spells. For real, I've been death touched by an enemy Mage that shot a single lightning bolt on me when I had 380 health. Sounds like yet another coding issue.
On the upside, the dumb elites/cheap enemies that you expect or already know about give you a reason to use poisons and such unless you're going to be dumb and exploit smithing/enchanting for 500 damage weapons. On that first boss I was getting sick of being one-shot, so I looked through my inventory. I had a poison of paralysis (3 sec). "Hmmm" I thought, let me see what this does, and put it on my bow to pull him with. I laughed pretty hard at what happened next. When I shot him with the arrow and he got that green "I'm poisoned!" glow, he became
stiff as a board and slowly fell backwards like a door closing. It was pretty funny. So I shot him a few more times, and by the time he reached me he was at 65% health.
I'm currently playing a "Mage Killer" character, since a) Destruction fucking blows for the player and I hate Bethesda for this and b) Enemy Mages are the only issue in the game other than the dumb two-handed shit. I am going my way up the Alteration tree and will have 85% resists from that tree alone (Breton). I'd really like to add in shock spells with this build to drain enemy Mage mana (heh, useless really), but it doesn't do enough damage stilll even with mods to warrant using.
Oh, and besides having maximum resists and maximum physical damage reduction (for 60s), Alteration has one of the cheapest spells in the game against anything but dragons.