There's some paint flaking on the intakes, so those are undoubtedly metal.
Looking at the rest of that pic, some of the parts seem a bit glossy and the edges bulge a bit near the seams. (classic signs of die-cast) I'd say the upper legs and lower torso are also metal. Probably the lower legs as well.
I can't see anything else that looks like metal to me; besides the screws and maybe the shoulder and knee joints.
Looks great now. I'm impressed. Though, as nicely as they hid some of those Imai joints, with the reduction to 1/55th scale those joints must be very small now. I suspect this thing will be a bit delicate. Especially around the wings.
Not long now.
Yeah, the potentially weak/delicate joints are a concern of mine, too. I had a chance to handle a sample at the Toynami booth at Anime Expo, and while the fighter mode seemed to lock up pretty tight, the robot mode had some joints that, due to their extremely small sizes, seemed to be easily breakable: the neck joint, the wrists, the fingers, the shoulder (where the arms swing back to transform to fighter). The rest of it seemed pretty tight, though I wonder how well the knee and arm joints will handle repeated transformations. I miss ratcheted joints.