On the plus side, most players will go insane painting enough goblins for a 2000 point army.
Seriously though, I think it is a good selection for an army and I wouldn't say it's overpowered. There are not many loop holes, exploits or power-game combos in a Moria force compared to Mordor, for example. You have to ally those in.
A well build Moria list, well played, would be a challenging army and I think that's exactly as it should be.
The available Monsters are effective but are also very expensive in points (and real money) (unlike a Mumuk which I believe is pretty underpriced). It has only a small selection of Epics which complement the army nice but are not underpriced / overpowered (Druzag is great but even a Captain has a good chance of taking him out on a Duel). The core troops are reasonable, unless someone decides to proxy their entire army as Blackshields or Prowlers.
I agree that the Giant Spiders are great cavalry no doubt but D3 is pretty susceptible, even to the weakened bow fire in WotR. Still these are some of my favorite Evil forces and another reason I enjoy my Dol Guldur force (allying these in). Several Formations, 2-3 Companies large, zipping around the flanks can really give your opponent something to worry about. You may not survive a second turn but you could do major damage on the turn you do hit.
Don’t forget the Spider Broodlings either. Though only D1 in melee (squish!) they’re Ambush combined with other special rules makes them a great little surprise to spring mid to late game and it’s very easy for your enemy to forget all about them after you initially told him you have a couple Companies of them in Ambush since they are just not a very attention-getting unit.
Druzag has proven my biggest PITA with this army. My opponent has been very good about popping his free units (usually Wargs but sometimes Spiders) behind my Formations and getting off some crippling charges. But the spells of Ruin have been just as bad.
I have faced Moria with my Wood Elves at 1000, 1500 and 2000 point levels. I have won each game though I'm finding as the points increase it's getting harder to do so. Some of the more potent monsters can be brought in and the number advantage increased significantly. My opponent, who has been playing Moria-based armies since ever getting into SBG before I did, is good with their strong and weak points and is a solid builder and player. I have an incomplete BR (pics are up but I never finished the narrative) from a pretty large game I played against a solid Moria force back in March. It included about 18 Companies of Goblins, Balrog, Druzag, Spider Queen and Spiders.
http://tac-me.net/index.php/battlereportslotr/lotrbattlereportswotr/74-br-wotr-26mar11My opponent “babyed” his Spiders a lot, fearing all my bow fire against their D3, so they weren’t too much of a threat, and with Legolas in my army the Cave Trolls were more of a distraction than anything else (they would have done better kept in reserve and coming up behind the main force I think). He also fielded the Goblins with Shaman and Drummer to really get their speed going, but due to the Formation sizes found himself limited in his move options a bit.