Though this game was completely different than the first (you explained why above), graphically, it makes the SMB 1 look dated. It's amazing how much they were able to squeeze out of the NES for this game. Granted SMB 3 was impressive as well, but SMB 2, a sequel to a game for the same console with dramatically better graphics is unreal.
I've never played the Lost Levels (SMB 2 in Japan) but I can see why Nintendo of America didn't want to use that one. The graphics are essentially the same as the original.
Yes they are. Every keeps saying it's crazy hard too, so, someday when I have played everything else ;)