Academy's B-17's build up, pretty straightforward, according to the instructions. All of them, from the B through the G series, assemble very well. A couple of points off the top of my head: if you build the bomb bay open, be aware that the bombs can pop loose during the rest of the assembly--and can't be put back (not enough fiddle space once the fuselage is closed); if you build the bomb bay doors closed, you'll have to sand down the doors--as they are too large to close. The radio antenna, on E,F and G's,is pretty fragile. Either be very careful when you sand the fuselage, or else remove the thing and reattach it later.
Which type are you working on? Maybe I can be more specific, although they are not any more trouble, with no particular quirks, than any other large bomber model.