Ah yes, I dig Opeth. They're pretty original, I haven't heard really anybody that sounds close to them. I hear a bit Opeth in Gojira's music, but maybe it's just me. Gojira strikes me as a cross between Opeth and Meshuggah.
The singer (Mikael ?) has a killer voice, and he's a hell of a guitar player. The music is so creative, it's like a journey listening to it, it takes you to different places, almost like a story. It's not one dimensional at all. They'll be hammering it out for one section, with full on blast beats, heavy guitars and growling vocals, and then they'll break into a mellow passage, with clean singing/vocal harmonies, acoustic guitar work, and melodies. It's a trip, but they do it in a way that it all fits together and works and doesn't sound out of place or too sporadic. I don't know how they do it, but they're intelligent musicians that write good, creative intelligent music, that's all I know.
They put on a good show live too. Saw em once on Gigantour.