If you hated this, go watch Neil Marshall's Centurion (2010)

A much darker and cynical movie with more competent direction, screenplay and much more involved actors. And Michael Fassbender (the android from Prometheus) is great in it. Also, it actually revolves around the lost Legion and not some annoying kid Caesar or "the" sword. Better than The Eagle (2011) too.

www.imdb.com/title/tt1020558/