The leg armor looks a bit organic, you may want to sharpen up the edges a bit so it doesn't look rounded, it makes the armor look like it's bulging or living- its especially evident in this picture on the sergeant's right shin. I think the chestpieces are a bit puffed out too, but that may be a stylistic choice. Finally the shoulderpads need to be a wee bit bigger, they look squat at the moment. I love the poses, very imposing and Space Marine. The backpacks also look like they're cool, I wish we had a shot of those.