I think the 60 was the most fun mechanically as far as classes being more centered around a certain spec whereas in the expansion one class can substitute another, such as holy pally and priest. I guess its bias'ed that I played a mage and a warrior where you really couldnt substitute those (try tanking UBRS as a prot pally). I think the prospect of some classes being better naturally than others in some aspects, druids and locks pvp, because then you dont have everyone doing the same thing. 70 wasnt as enjoyable as I thought it would be, but I think the storyline of WotLK will fix it, hopefully. I wish they added another class other than DK, that way you spread across the ammount of people creating a new class in the starting area day 1 by 1/2.

One thing i hate the most is farming motes of mana in netherstorm outside of area 52 with the ravines and killing the mana wraiths halfway up the ravine, making it physically impossible to loot, oh well