Yep! The fact that the GBA has many quality, free emulators is a big bonus. It allows people with no access to hardware to participate. At least one (no$gba ?) even has a built-in debugging interface and can be debugged with gdb!

I did my tiny experiments in homebrew dev on an emulator. A year later, I bought a flash cart, booted up my old program on a real device and it worked! :D

no$ is awesome. I used (and paid for) it for all my professional development when I was writing GB/GBA games.