I love my Tower Rook, but unless you win by level 12 or so, Tower Rook builds are useless.
Tower Rooks builds are *terrible*, and I mean *really terrible* by late game. Your damage is extremely mediocre, the shoulder upgrades AND tower's damage is something that any demigod can just shrug off, and rook is significantly more squish than any other DG.
His only "defensive" skill (eat tower) is easily interruptable, and takes forever to start "ticking". Boulder roll is okay, but by itself is not enough. Sedna heals, Oak & QoT shield, Erebus has bat+mist+insta-bite-heal, UB isn't that squishy (again, we're talking late game) and is fast, and Regulus/TB shouldn't ever be in melee range anyways (plus TB has a few different escape tools).
Late game, a Tower Rook is just a crappy, slow, melee DG with sub-par stats. Defenses tend to be pointless by this point, and it really shows; Oak and Sedna, in particular, can totally ignore any size tower farms.
Not to mention that with his lack of DG killing ability, Rooks are generally starved for cash.
This isn't to say that Tower Rooks are weak all-game, they are very good builds early and mid. Perhaps towers should have a higher mana cost, a longer cooldown, and should last longer. I seriously believe, however, that Rook's towers should be boosted by the citadel upgrades, or that his shoulder&tower damage should be based upon his weapon damage (i.e. get ashkandor+god power 3 and his ranged passive damage should be sweet).
All you have to do to beat a team with a tower rook is survive to later game, and focus fire the rook when he's alone and doesn't have many towers up. Get to level 15+, get 10k gold worth of gear, and there is literally nothing a rook can do but hide behind towers and hope the battle doesn't focus around his farm. I.E. be worthless.