Pretty sweet!
I'd have liked to see more use of the gravity gun though, it seemed secondary to the other guns.
I went psycho on the last level and used all 100 rocket launcher shots like crazy (I didn't even know it was the last level at the time). Max rocket ammo obtained by committing suicide over and over in Canada after picking it up! xD
Anyway, I liked it. It was a good platformer. :)
Wait a minute! I never read the instructions, so grenades and slo-mo were absent in my playthrough! D:
All the more reason to go through again I guess!