its honestly not really bad. it's the first version of the game i played through to the end cause it was portable.
it's harder, because you see less of the screen, which makes some bosses harder (mainly the fire one and the final battles) and it makes some platforming harder because you see less ahead or below, leading to one or two leap of faith situations.
but it otherwise plays perfectly fine. if you know the levels from the snes, it shouldn't be an issue, otherwise, first time players should probably opt for bass because of his double jump.
if you can play either, of course, go with the snes version, but if you can only access the gba one, it's fun enough