What faction d'you play?
I've been reading extensively on the game, and it turns out Elves are slightly OP. The reason is they can produce Lorien Warriors, Pikes, Mithlond Sentries, Silverthorn Archers and Mirkwood Archers all from the same place. So essentially all they need are 2 buildings, one rax and one stable(for Rivendell Lancers). This gives them unmatched flexibility. To add to that, they get some excellent heroes. You've got Haldir for LD, Thranduil to murder any heroes, and Lego who is just ownage.
Mordor are horribly UP in the game. Firstly, Orcs cost 25 more than Goblin Warriors, yet they move slower, don't have the poison ability, and have slower attack. Same goes for Orc Archers, they cost 100 more and don't get the poison ability. To add to that, Nazgul are very very weak to ranged fire now, 4 unupgraded Goblin Archers can take out a Naz. In my opinion the only real chance Mordor has is to get out Black Riders fast and to back them up with Haradrim and Soldiers of Rhun with Drummer Trolls for LD.
Goblins are really strong, they are so fast that they're always a step ahead of you. They get counters for nearly everything. They've got Shelob, who absolutely owns at taking out heroes, then they've got half-troll marauders, which own cav, they've got Drogoth who can fly around decimating infantry, and last but not least, they've got Spider Riders, which are insanely fast, and can counter their own counter, pikes, because they can switch from bows to swords at leisure.
Isen seem to be left out, they are really not very strong this game. Now Wargs are essential to any of their strats.
Haven't really seen MoTW or Dwarves much, so I can't comment about them. However, I have heard that Dwarven Guardians counter cavalry, which is insane!