Can't comment on the PvP as I haven't done any.
I have Pandaren Loremaster and until Dread Wastes I found the story and lore very good and engaging. Dread Wastes is the one sour spot for me because by about half way through you are thinking " for the love of god, please don't give me quests to feed this damn bug".
The required Rep grind ( and yes it pretty much is required if you plan on getting anything really) is probably the only thing ticking me off about the entire expansion so far. Its boring and despite how they tried to sell it, insanely repetitive. I've only been doing them for a few days now, and I feel like all I do is Dailies with a few other bits in between, really annoying.
Instance runs I'm actually enjoying, and although they are really easy, I'm ok with that. I didn't get annoyed by the Wrath ones, although I will admit that even the Wrath ones were harder than this at the start.
Professions would actually be in an awesome place across the board, if it wasn't for Spirit of Harmony. While I am really enjoying playing my Elemental Shaman, the fact she is mining/herbing leaves me feeling hamstrung when it comes to the Spirits. Sure I can convert them into some useful things, but it feels like such a waste.
Right now I would give it a 7/10 with the possibility of it going higher if they do something decent with the daily grind ( hint: this new idea for Rep they have ain't it), make Spirit of Harmony BoA ( I don't really want to see it BoE, I like that its not just another mat, but being soulbound is just too harsh) and then whatever the future may hold. It could honestly turn out to be my favorite expansion of them all, its definitely far exceeded Cata, but definately behind Wrath and TBC.