top of the water is really good especially if you use one of the water mods and up the resolution to 1024 or higher......under the water just svcks though. this isnt 1999 they can do better than that.
low end weapons and armor some of the best ive ever seen......high end gear is awful though.
random mini quests, i actually like doing those.
the feel of magic although i miss spellmaking itself
combat is lots of fun although DW is OP. not a huge issue for me since i started using blocking and have come to enjoy that even more than DW.
main quest was fun.
gameworld itself is fantastic. bethesda may be average or at best above average in many things, but they outdo everyone in gameworld design by far.

side jobs are fun.
even after 160 hours still dive in and catch fish and butterflies. you would never have caught me playing a fishing game or butterflying netting game prior to skyrim
alchemy is better
probably some more but thats all that comes to mind for now.