I was thinking about this conversation because lately we've been seeing a lot talk about robots now for military purposes. When I see like DARPA developing robots and how they look, I hope they're just experimenting or appealing to people's vanity in order to get public support. The one thing I see common in fantasy and real life is the robot soldier of the future has to be made as human as possible. Realistically the human form is limiting in combat. If I looked at how movies portray military robots and which would be more realistic for combat conditions than most, I would have to pick the movie Red Planet.
It's a fast, nimble, and stealthy configuration and not just because it was portrayed like that in the movie. It can stand like a bi-ped when needed and travel on uneven terrain better because being on fours can keep it stable at high speed. Now the trick is the power source as with everything. No technology exists today where you can make a robot operate on its own for days, weeks, or months at a time.
I think adoption of human form may also depends on mission profile, i.e. disguised as human for infiltration.