I myself came back to wow last december and then quit last april. A few reasons why the game isn't worth playing right now IMO:
1) PVP is just crap. Complete crap. It's nothing new that it's imbalanced, but its WAAY imbalanced because blizzard is happy with current PVE balance and isn't going to change. In addition, most of the players that participate in it are just elitist douchebags. For starters, I had some priest come up to me and try to duel me when I was re-entering the game for the first time and had no action bars. I declined and explained why, so then he starts calling me bad and then insists that I need to buy arena wins from him, in spite of the fact that I already had a much better PVP history than he did (ratings, titles, and all; my best being duelist, his best being challenger.) This was a sign of things to come, as most players behaved in a similar manner as I continued on. The game isn't at all like I remembered (for one, if you were anything less than gladiator material, nobody would even think of buying arena games from you...yet here we have even a challenger being an elitist douchebag.)
2) Most people still just spend their time endlessly running/flying around in circles in their preferred capital city, because there really is nothing to do most of the time.
3) Current tier is going on...a year now? Probably not going to be anything new for a long time from now either. In LFR I tested it once; I can literally just randomly click lifebloom every three seconds and it actually appears as though I'm doing something, and I never get kicked. The content dies so fast you don't actually have to do anything. Of course, I'm coming from a time long before LFR, and every time I saw LFR, it set a new lower standard of "I've never seen so much fail in a raid actually succeed."