I saw this on Saturday, I enjoyed it a lot.
I thought the low budget really showed in the CGI, the planet was beautifully conceived, but unconvincingly rendered, and the green screening effects really sucked. I also thought the script was clunky and the acting mostly poor.
However, Vin really shines in this and makes it a lot of fun to watch, the parts where only he is in the movie are the best bits. The action was non stop, quite entertaining, and there a few effective moments of tension. Good to see Katee Sackhoff up on the big screen, and the prosthetic effects were fantastic.
I give it a B+ for an A-Movie, or an A+ for a B-Movie.