To be honest, I didn't expect much from this game – lacklustre title probably doesn't help. It's fair to say that the game is anything but lacklustre – it's clear that the makers of Space Marine are fans of the fiction and have poured detail and art into every nook of the game.
The fiction shines thought – from the 40k Marines being giant hulking humans, through to the Orks and Chaos – it's all there, and I can't find fault with any of the represented story.
All that aside, what this game has in spades is FUN. You feel huge – space marine, power armour, melee and ranged weapons. The combat is something just a bit different from anything else, with a sort of mix between ranged and melee. You can't really play it as a straight shooter as there's too many dudes who'll swarm you, and neither is it a pure melee game. It's something in the middle, a ranged brawler of sorts, and it's visceral in how it comes together.
Some of the battles in this game can be frustrating however – the use of check points is imperfect, and the final boss fight in particular may induce moments of controller-breaking rage. If you're prone to frustration, this might not be for you – and it's for this reason alone it doesn't get a five star rating.
If you like games like Gears of War, you'll probably like this. They're not 100% similar, but there's big dudes and lots of blood. It's a ride :)