Unfortunately, this movie is not shaping up to be very good. First of all they rushed it's production, which started very recently (around December or so). Also, although they are maintaining the look of the monsters, locales, etc., the movie is not about monsters invading from hell, and it doesn't even take place on Mars.
The official story right now is that it is a "loose" translation of Doom and involves an unnamed planet and a group of Marines stationed on that planet fighting the other inhabitants of it who have been transformed into monsters by some sort of horrible plague. Again with the plague....I'm tired of Hollywood ripping up the core material. They don't have to honour it exactly, but changing the things they did make it very "un-Doom". Will I still see it? Of course, but I'll most likely wait till video release.
Oh, and the LOTR actor it also stars is the actor who played Eomer and Vaako in "Chronicles of Riddick" (really liked that movie). There were conflicting reports that the Eomer guy was the lead marine and The Rock was the Sgt., but now it seems that their roles have changed. The Rock is the only "pro" wrestler I've ever respected, and at least, even though they're mucking with the material a lot, it should be a fun, gory, action-packed popcorn flick.