It's got some great sets and costumes, a fantastic, frankly groundbreaking soundtrack of calling vocals, and spectacular deeply theatric moments, basically any time the characters aren't actually speaking is OK. The dialogue is fundamentally awful, Romans are one-dimensionally bad, absurdly condescending and arrogant, and barbarians good. Obviously the writer wanted to make this a commentary about current politics, referring to Icenians as "terrorists", a concept which did not exist at the time. In fact, many lines such as "For God's sake!" would not exist for this setting.
I don't suppose anyone could tell me the reason why all the Roman soldiers have cockney accents either.
To watch this film, you've got to have a sense of humor for the dialogue which is utterly painful. The Romans are written so badly on such a deep level one can take amusement in it. But it can't be described, laughed at, and appreciated as a bad B-movie, there are quality stirring dramatic moments there and any humor you see in it is killed by the prolonged gang rape scene, which is not a gratuitous addition but a serious, fundamental part of the historical accounts of the real Boudicca.
This film is without compare in its strengths and weaknesses and I'm wholly at a loss to classify it or say exactly how one should appreciate it. You will have to decide for yourself and tell me.