Actually, they are the only adatper that works correctly with rumble packs and memory cards (although retrozone's attempt has some basic support). NO other adatper has that. It also is not at all limited and gave me the truest feel when playing N64 games on the PC.
They are absolutely not limited at all to one keypress. I don't know what bitter flamewar you happened upon but I can assure you there hasn't been a better interface that i know of for n64 controls on the PC since. I've had 2 other n64 interfaces that were absolute crap. I just wish wishtec was still selling these.