-Regenerating health
-Replacing strength, edurance, etc with just health, magica, stamina, (I know the system in oblivion needed to be reworked, but they went too far, I don't like how you can't increase your speed or the amount you carry), as well as the different stats races and genders had
-Getting rid of hand to hand and acrobatics
-Armour doesn't degrade anymore
-Fewer armour/weapon types (no silver or mithril, in addition to the fact that you no longer need a silver weapon to harm spirits)
-Combining longsword and short sword into just sword
-Fewer spells, diseases, and enemy types.
-No more dark dungeons (underground caves are one of the two places in the world with absolute darkness, the other being the bottom of the ocean, they shouldn't be well lit, even with numorous torches on the wall)
-No reason to sleep (I know the whole you-need-to rest-to-level system was bad, but I find it funny how my man character has spent almost an in game year and only has one hour of sleep)
-Intros to Thieves and Dark Brotherhood in Oblivion were better
-No ranking within guilds (seriously, in the college of winterhold, I immediatly go from student to arch mage in a matter of in game days)
-Everyone in the cities spouting the same one line to you if you get within 10 feet (this is even worse than when the npcs have really disjoineted conversations in Oblivion)
-removal of disposition and morality systems (again, these were bad, but shouldn't have been taken out entirely)
-All horses have the same health and cost (exception being Shadowmere)
-removal of arena
-no one comments on your actions (the Black Horse corrier was something I kinda liked)
-the removal of enchanted arrows (I know this is a balancing issue, but I would like at least a small fire/ice bonus to my arrows)
I know a lot of these were added to make the gameplay smoother, but I still think they should have done a different approach