I've been playing since like 2005 and honestly MoP is my favorite expansion since Burning Crusade. a lot of the quests are incredibly frustrating, but it just feels better when you hit 90. I do agree with a previous poster about the LFG system, I truly miss spamming trade chat to find a 5 man group. to anybody who is just starting leveling through Pandaria, I suggest taking the Townlong Steppes quest lines rather than going to Krasarang Wilds. Townlong Steppes had some of the most fun quests I've ever done.
PVP is shit now though. mostly world PVP. it hardly even happens outside of planned events. I'm on an RPPVP server right now because some real life friends were playing there, and the entire time I've been there since WOTLK I haven't been in an open world fight that I didn't start. even the level capped kids who I frequently passed while leveling didn't so much as touch me. it's pitiful. I guess I could transfer to one of the release servers and be with all of the other OG WoW homies, but forget about starting out as a fresh 90 on a well-established server.