I just got into this game a few days ago.
I love-
The talent/skill tree system.
The freedom in builds and gear with no class restrictions.
The way skills are gems.
The potential fun of a cutthroat league. Or cutthroat hardcore league. However, haven't done any pvp yet, so that is why I qualify this with "potential".
I hate-
The developers lack of interest in any sort of real money auction house, and the economic system in general. Removing gold isn't going to fix anything, it just makes it annoying as hell to farm because farming at high level is only slightly faster than farming as a newbie. Lack of a real money AH will not stop money for item trades, but will penalize legit players and will make it easier for farmers to make money farming. Bad.
Inventory size. So annoying, you pick up 6 items and you are full sometimes. Look at grimrock for a great inventory limiting system. You need strength to carry more stuff. It's annoying as hell that my 200 str Templar can carry the same amount of stuff as my 15 str witch.
Potion spam. Nerf damage all around so we don't NEED to spam potions, reduce the rate at which potions fill, limit the potion bar to 2 potions (maybe 3), and add a 1 minute cooldown on using potions. It's just a dumb game of "hit your potion key every 10 seconds" with the current system.
Overall, I am highly addicted right now, but the parts of the game I don't care for too much will probably cause me to switch over to D3 when it comes out.