The American building is both impressive and a photographer's nightmare - the whole end wall is glass, so looking that way creates extreme glare, but looking from that end things tend to go into the shadows...
But all the same, it is a fantastic building containing a great collection - I don't think there are many places outside the US where you can see a B-17, B-24, and B-29 together, never mind a U2 and SR-71 alongside a F-111, F-4, and A-10... 8)