Very good. Especially robot mode - very posable. How do you get the knees to support the weight when the leg is bent? It looks like the knee joint is a Technic pin, which won't do it on its own. Does it rest on something underneath?
People who build robots have to be good. People who can make them transform into jet fighters which are actually cool are even better-- and this is one of the best I've seen. The fighter design alone is enough to merit five Severed Minifig Heads. The lack of text leaves me a little confused about how the jet and robot versions actually go together, but it doesn't reduce the sheer awesomeness of the design.