Frequently people say that tonally the Flea soprano is "it's own thing." Compared to more traditional ukuleles, do you consider the Flea soprano closer to certain concerts or tenors? Pineapples? Hey, it's a Monday...
I suppose it doesn't have the same zingy kind of soprano sound that you might find in a nice lightly built solid wood traditional instrument, but then again, there are many other ukes that don't have that sound either. I have heard some luthier built instruments and laminated imports that don't have those tonal qualities. That said, the flea still sounds like a uke. You could not mistake it for anything else. I have heard some in live and recorded settings that sound great. It is perhaps a bit less treble-y and has a little more mid range or warmth.
They play really well and have a nice set up with really good action and feel. They are well in tune with a really nice tonal balance. I have played and heard solid wood instruments that don't sound or play anywhere near as well.