I'm actually playing one right now (a fighter) in a game that's intentionally fairly high-powered, and at 16th level (or ECL 16) it's not remotely game-breaking.
He dishes out a lot of damage and has excellent SR and saves, but he still doesn't come anywhere near in power to single-class casters... If you can handle those at high levels, you can handle a half-celestial. As a matter of fact, I'm now convinced that playing some sort of ECL+ race is the only way to go when playing a fighter at high to epic levels, unless you enjoy being a sponge for abuse and don't mind dying frequently to ensure the casters get their spells off unmolested.
He dishes out a lot of damage and has excellent SR and saves, but he still doesn't come anywhere near in power to single-class casters... If you can handle those at high levels, you can handle a half-celestial. As a matter of fact, I'm now convinced that playing some sort of ECL+ race is the only way to go when playing a fighter at high to epic levels, unless you enjoy being a sponge for abuse and don't mind dying frequently to ensure the casters get their spells off unmolested.
