Nobody's mentioned it yet, but I really liked the beholder's antimagic zone; its interesting, given the number of zones available to high level leaders and controllers, many of which can be quite powerful (at least, I love 'em).
Yeah, antimagic field is pretty darn cool. You could dress up the beholder's lair with some permanent zones to give him even more incentive to push/pull/slide the PCs around into dangerous spots. I can only imagine fighting this guy, having his way with me at the start of each of my turns! Mounting a serious & consistent offense against the beholder seems like a real challenge, even at epic levels.
Am I the only one who thinks that 2d6+7 isn't enough damage at level 29? Some of the higher-end players at this level will have upwards of 200 hitpoints. The Beholder gets a lot of attacks, but the damage is really low.
I think I'd probably still run this guy with my 75% hp and +1/2 level to damage which would turn the 2d6+7 into 2d6+21 damage - much more epic!.