Shane Hurlbut, ASC, used a 5D2, 7D and a 1D to shoot 70% of his last feature Act of Valor. He has the advantage of being an excellent lighter and access to an awesome post-house to release a really good looking film.
That being said, every camera has it's issues and workarounds. Lighting for DSLRs is absolutely necessary. If you can light, then I don't see an issue with using the 5D. As to the question of "film" look, check out Act of Valor.