I've been messing around with some of the new cards. There are some neat things in there.
Shadowmeld (elusive/untargettable while ready) allies seem pretty powerful for establishing board position. I can see a healer deck with those.
Locations seemed pretty strong to me until I realized that you could only have 1 face up... There is one that is tap to make the next ally you play -2 cost. I guess you could tap one in play, lay another and tap it to play a 4 cost guy on turn 2 which is still pretty good. You might even be able to get a really huge guy with all the diplomacy keywords in the set (dwarves cost 1 less! DWARVES!!)
The really cool one is the 7 cost summon 3 or 4 (i forget) pandaren which all boost each other. With the right druid deck, you can get that out on turn 4 or 5. Add to that the feast of winterveil card that adds types to allies, the pandaren could get stupidly huge. Especailly with the 7 cost druid ability that puts 5 1/1 tokens into play. It's a multiple card combo, so is automatically sort of janky. Should be fun to build though.
Speaking of druids, there are 2 that come with forms as their flip ability. Seems strong. Auto cat (or bear) form that can't be stopped with more room for other things is fairly awesome.
For rogue, there is more low cost discard, this time random. Over all it's a pretty cool set.
PS. I built TIMMO! (With the betrayer's warglaves.... heh heh)