I played Death's Reach, Kingdom of the Ghouls, and then DM'd Prince of Undeath.
I have bad news, Epic is broken.
As a paladin I stunned my way through elite after elite. The designers gave way too many "control" powers to non-controllers. Paladins stun, rogues stun, rangers immobilize etc...
The power level obtainable by players is too much for the monsters. Players can boost their defenses with feats and items to be near un-hittable. They use interrupts, and action points, and stuns to maintain an action advantage of 2 to 1 or higher. The players get to act 2 times more than the monsters. Then pile on top of that interrupts like Shield that cause misses. Causing a miss is just as good as a stun if you compare the effects the two have. Both cause the player to have a damage advantage.
You've got to do a lot of work converting the monsters to the new MM3 and Monster Vault guideline power level.
1. Easy fix: Double the static modifer of all damage so 2d6+6 becomes 2d6+12. Brutes need it tripled 2d6+18!
2. You've got to give Solos and Elites their actions back. Give every Solo an extra standard action! Yes the old solos were designed to do 2 monster damage per standard, and the new ones are supposed to be outputting 4 per round. Let them automatically end stun and daze after each standard action. Let Elites take immediates no matter what, or just let them spend their action point to remove an effect.
3. lower the HP of Solos by 1/5th
give all Brutes +2 to hit.
lower all Soldier's to hit by -2, and let them all mark even on a miss!
4. Have a serious discussion with your players and try to convince the non-controllers to dump their stun powers and their other "controller" powers.
Consider some houserules. After the first few weeks, all of us players were fed up and bored of Epic, so we agreed as a group to try some houserules. First being that Stun was downgraded to Dazed on Elites and Solos. You should have seen how fast everyone dropped their stun powers. All people wanted to do was stun elites and solos, it wasn't fun stunning anything else.
That should do it.
P.S. The worst boss fights I ever saw were Doresain and Orcus (separate encounters). Doresain was stunned (save ends) by a Paladin, his Balor dominated by a Barbarian! With Orcus, he never hit once with Touch of Death because every time it was interrupted by some random player interrupt.