Regardless of what class you chose, you could still go and do everything and anything.
The horses are completely pointless, seeing as you can just map travel. Honestly, the only use Shadowmare got out of me was as a walking treasure chest.
The races now all feel the same. In Morrowind if you played as an Argonian (which I did a lot), you actually felt like you were playing as something other than a scaly human with big ears.
Bandits with Daedric Armor. That's all I really need to say I think.
The map is smaller than Morrowind's. Sure it looks a hell of a lot nicer, but my point is it used to take a good hour or two to get from one end of the map to the other, finding monsters, camps, interesting individuals and caves to explore along the way as the in-game days trailed by, not a leisurely Sunday jog where, rather than feeling like you've done some real exploring, you're literally tripping over locations left and right and make it to the other end of the map in less than 15 minutes.
My biggest peeve, however, is that THEY TOOK AWAY THE SPEARS! What's wrong with spears? I always took the Spear skill in Morrowind because of the extra few feet of range.