I took a look at my BI-1 yesterday, and was able to dry fit most of the major parts together. All the reviews were right- nothing fits with any degree of accuracy at all. I got the wings glued on (jumping the gun a bit, I know), but actually achieved better fit after the locating tabs were sliced off. The fuselage halves need a bit more sanding still.
The rear tailplane is one piece, which "slides" into a slot in the rear of the AC. It's supposed to, anyway. It stuck out too far, and once I gouged out the slot enough to make it fit, huge gaps are apparent everywhere. I see much putty and superglue going into this area.
The good news is that once the major components are together, everything else is just little bits that glue to the outside of it- no more major plastic surgery (knock on wood).
Despite the problems I like the kit so far. A rare subject, and a nice little (4") kit to fill the shelf. I could have fun with this one!