The thing that is the most appealing to me is that I really want to see, in the Beta, the change of the class talents, spells and other updates, and how well they vibe with the new instances/raids and group play. For example, I play a DK Blood tank, and as most of you know, they arn't very AoE friendly. I'm interested to see if the stability of Blood AoE play (and AoE tanking in general) has been increased when going up against certain mobs, whether one aspect needs to be buffed up a bit or sending feedback about how something new works great and how much I would really enjoy seeing it in Retail. Or whether something needs to be CC'd in effective situations (since CC has been pretty much ignored in the recent expansion for the most part), and if something needs to be tanked in a certain position in coordination with efficient group DPS. This makes me wonder even more now that I hear the new instances are not so much a face roll like they have been.
Also, I would like to know my reaction and feelings toward the new class trees.
Thanks for your time.