Was definitely fun as hell but here are 2 words of warning so you don't fall into the same issue I did:

#1 When I did completed the wrathgate achievement quest on all 5 characters, it kicked off 5 cutscenes at the same time. Besides the fact that it locked my PC up for a good 2-3 minutes while it was loading 5 videos, it started about 1 second earlier on my main than my 4 alts, and since its playing a video not using in-game sound, it played sound on all 5 cutscenes. Was hard to hear what was going on since it was echoing like crazy. When you complete the final quest you might want to do it on 4 alts, escape out of it, then do it on your main and actually watch it.

#2 Battle for undercity - I thought this was going to be quick. Its not, not at all. It took something like 45 minutes. My wife was pissed. I told her I would be done with this last quest in about 5 minutes (we were leaving somewhere) and then I started the event and realized the battle didn't even START for 5 minutes. Then you're stuck waiting for thrall and everyone while you follow them around, VERY VERY SLOWLY. Fun event but make sure when you do battle for undercity you have plenty of spare time. You might also get lucky (unlucky?) and join when its almost over and insta-complete it.