PC World, 1 out of 5, GTFO.
I won't post my full SP review until I finish the campaign. But I will say I played almost 6 hours on hardened mode and I am still not even done. So anyone who claims they beat it in 5-6 hours is either lying or played on pussy mode. I've spent time looking for the dog tags, audio logs, and the lost marine weapons. By the time I beat all of SP I should be around 8ish hours logged. Not too shabby.
LOLpcworld.