In the game he's not. In the film he is.

He starts off as a very cool character in the game and then when he finds out the truth about Nibel he becomes a bit down in the dumps, but then he drags himself back up in the games final chapters and resolves to beat Sephiroth and save the world.

It's the film that's the problem as it just forsakes all the character growth Cloud as been through and casts him as an unlikeable 'woe me' git.