Perhaps this is purely my own observation, but I feel melee combat had the least improvements in terms of the different varieties of combat. Magic looks amazing in Skyrim. I would argue it got the largest make-over and actually has me interested (which is strange as I never use magic in TES). Archery is finally getting needed improvements with being able to zoom in, slow time, do a lot more damage, etc, various aspects you would expect to see in a FPS game that should coincide with ranged combat. Melee is Oblivion with a new paint job. Here's why:
Besides the new animation system (which is great), more blood splattering (okay that's fine) and finishing moves (something different), it's just the same old Oblivion hack and slash. Heck, even the power attacks you will gain as you level melee are the exact same (disarming, paralyzing, knocking over, etc). I just feel that Bethesda Game Studios could have done A LOT more. Am I asking for too much? Perhaps. Are my expectations of game mechanical improvements unrealistic? Maybe. This doesn't change the fact that Skyrim's melee combat is almost identical to Oblivion. The transition in melee combat from Morrowind to Oblivion was huge, but why not Skyrim?
Melee combat was completely horrible in Fallout as well, which you might argue is really a rpg shooter. So why have melee combat then? I just feel BGS has not found an adequate way to really change and revolutionize how melee combat can be performed. So instead, they made the animations smoother, added some more blood splatter, tried to make the npcs seem more alive, and put finishing moves in to try and take our attention away from the same hack and slash formula. Perhaps I'm overly-critical, but it's because I care. BGS is by far my favorite game developer. Ever since Morrowind, I have been fully on-board with all of their games, but melee combat just doesn't seem to be making the transformation magic and archery are getting. Anyone else feel that melee is somewhat disappointing? If not, feel free to explain why.
Just a few ideas for how melee could be better:
Combo attacks
Counters
Less basic hack/slash and more complex and integral moves (perhaps could evolve as you level your skill)