Basically one of the biggest cop-outs in the history of comics. I'm always shocked the MM #9 is so sought after because of how terrible the conclusion was in #10.
Torch and Subby fight to a stalemate/cliffhanger at the end of #9. There appears to be no way to resolve the situation. Then in #10, the authors basically acknowledge as much, saying that Torch and Subby agree that it's been a good fight and they should part ways with mutual respect. This all happens in 1 page, with text that says "Well reader, if you thought this was a tough spot, you were right, and that's what our heroes thought as well, so they decided to quit."
Has to be one of the Top 10 comic book letdowns of all time. If there had been Internet message boards back in 1941, the servers would've all crashed under the outrage. I bet there were at least a few early "fanboys" who swore off Timelys forever based on that fiasco (only to come back 3 months later, because after all, they're fanboys and can't help themselves).
Well Issue #9 at least had a full battle sequence and an awesome cover, probably one of the best from the whole Marvel Mystery run. Issue #10 should get the all the flack and little mention because it was a terrible cop out and probably one of the lamest endings to an extended battle that I have ever seen. Actually the ending of J.I.M. #109 with when Thor batlles Magneto was probably worst.