First, 3D is not an emulator, it refers to the native Dingoo games.
Apart from those emulators there are a bunch of homebrew emulators, for example:
GnuBoy (GB & GBC)
SmsGGOO (SMS & GG)
and a few more...
Most emulators work quite good. Though, SNES and SMD are slow and have some other issues too.