This is Digiko, dressd up as Garrus from the Mass Effect series. I had to drop his name in there because if I hadn't told you, you may have thought this was simply Garrus from the Mass Effect series.
The whole thing took around two months to build and cost $300 in materials. The Mantis sniper rifle is based on a Nerf Recon, and the suit is built mostly from EVA foam.
If you're thinking the eyes could do with some work, he says that's because they're not "blacked out", which they will be for conventions, etc. If you've ever seen an effects man, or an actor in an animal suit with "panda eyes", that's what he means; it helps create a seamless transition between the suit's eyesockets and the actor's actual eyeballs.