The DC fixes it a lot, actually.
The director's cut of Kingdom of Heaven makes it into something of a flawed classic, but yeah I don't like Bloom much in the movie at all. Balian's supposed to be a guy who's dealing with a lot of internal issues and somehow eventually comes into his own as somebody who can functionally be a leader of men, and Bloom just can't sell that at all. He doesn't seem like somebody wrestling with demons, or choices that could end in tragedy, or a guy who could lead people to resist some horrific siege. He seems like a kid constantly out of his depth who nobody could really have much respect for. And it makes moments where Ghassan Massoud or Alexander Siddig look at him as some worthy rival come off a little weaker as a result.
Admittedly I don't think Paul Bettany would have been much better in that role. And at the risk of coming across as boring? I'm totally willing to state that Russell Crowe would have been my logical pick. They'd have had to make Balian older*, but Crowe at least when he's on is capable of giving a performance that's subtle AND makes you think a bunch of battle-hardened knights would say "Yeah, I think this guy should be the boss."
Or maybe I'm just desperately wishing Hollywood would make my "Sam Peckinpah in Medieval times" movie.
*This would also probably require that the blacksmith backstory, and Liam Nesson as his father be taken out. I'm cool with that. Because even the Director's Cut doesn't sell me on how Balian can kick ass so well, and I'm way more interested in the knight stuff than how one goes about becoming one in the first place. Even more so when it starts up like a Robert Jordon novel.