This image grabs your attention, and it's definitely the best Grievous rendition I've seen. I've never been a fan of that particular character, but this image makes him more interesting. I agree that showing less of him adds to his menace. One particular detail I like is how you presented the general's lightsabers. The weapons seems to be an integral part of his structure.
The causalities you spread around the scene are good, but I especially like how you have the thermal detonator's ruby lights reflecting off the trooper's hand and helmet. You get the feeling that light is going to be the last thing the clone sees.