Well I'm amazed to say I'm loving WOTLK so far. So much so I've now got both my Shammy and Pala to 80 (I levelled them in tandem to maximise the rested bonus). The new zones are beautiful, the new quests are great fun (a few irritations but mostly a positive experience), the new instances are very well scripted and optimized for less trash and more bosses. As for rep grinds, well they are largely gone. You can easily ding honoured, in some cases revered, with all the major factions while levelling (or by catching up on missed quests at 80). Then if you don't want to do the dailies (which can be a bit of a grind) then simply use the new tabard system and wear the tabard of your preferred faction, jump in any heroic and earn several k of rep for that faction from a single heroic run. Genius system Blizz should be applauded for.
So far I've enjoyed running the heroics, done several on Shammy as dps and tanked my first on Pala last night. They are nicely challenging in freshly dinged 80 gear. Legion Inc did Naxx 10 man on Friday and we got the first two bosses down, almost a third. Was fun working it out for ourselves and not relying on WoWHead too much, felt like we'd achieved something. As for 25 man hardcore raiding ... bollox to that as always
As for PvP, just don't go there
Even on a PvP server it's possible to largely ignore it. My Pala got ganked once enroute to 80 (DK driveby while eating), my Shammy a few more times (as they are a free HK to almost all other classes these days) but nothing too bad. Ganking really hasn't been as much of a problem as I'd feared, and one great thing to see is that due to the Achievements system there are now quite regular raids to Stormwind and Orgrimmar to kill the leaders there.
WOTLK isn't without its flaws, but overall its a much better expansion than TBC was and takes PVE in a better direction IMO. As for PvP ... Blizz can shove it where the sun don't shine