I'll be different from the majority of rookies and NOT beat on the Buffalo. Instead I'll beat on the Bison, or PZL.30 Zubr, a medium bomber developed prior to the invasion of Poland.
A few gems from it's service life:
-Apart from the Polish Air Force, Romania showed an interest in the Żubr prototype in 1936, and wanted to buy 24 planes. However, after the prototype crash on November 7, 1936 over Michałowice with two Romanian officers on board, they ordered the PZL.37 Łoś instead (it should be noted, that the factory published a cover-up story, that the crash was caused by one of the Romanians opening the door during flight). The aircraft
broke apart mid-flight.
-The maximum bombload was 660 kg (1,450 lb) of bombs. This is a dedicated bomber developed in the mid-30s, mind you.
-Fully loaded, it could only operate from paved runways.
-The production models used engines 50% stronger than the prototype despite insistence of the designers that the airframe couldn't handle it. So they strengthed it by gluing extra plywood to the wing spars.
-The locking mechanism on the retractable landing gear was so bad that after a short while most ground crews simply forced it into a fixed down position.
Plus it was ugly as hell. I'd be embarrassed flying this hunk of poodoo.
It may be disqualified due to the fact that it was never used as a bomber in combat (though it WAS sent to squadrons to be used as such), and similar to the Botha, the head-slappingly stupid decision was made to give it to the training units. Most of them ended up going kablooie on the ground when the Luftwaffe came through, though they did capture a few of them, including a twin-taiflin prototype. Funniest part is that THEY used the thing as a trainer well! For longer than the Polish ever did!
So there you go. The Buffalo may not be the worst, but I'd say the Bison is CERTAINLY worthy of consideration.