its one thing to give the enemy a full stack every time you siege some worthless settlement. its another to give them free spawning armies that attempt to retake a settlement that they just lost (armies with zero upkeep). its yet another to make me siege edoras, beat a relief attempt, get pushed back, and lose edoras to 2 goblin generals.
all of these factors alone make it a goddamn inferno to try and play isengard successfully. right now im in turn 162 and have finally conquered Rohan completely (retaking edoras and warring the OOTMM), the southwestern part of Gondor, half of eriador (now arnor) and pushing both east against gondor, north against the elves and northwest against the other elves. with any other faction, by this turns im usually already close to winning the campaign, but isengard is ridiculously hard. easily the hardest faction.
what im trying to say is that if you want someone to play as them, give a warning or something.