I owned couple of those novelty keyboards and ultimately forfeited all of them for the weird reason: latency. I didn't know it was latency at first. It just like keyboard is faulty, it's losing keys, or producing more than it should.
But then I stumbled upon (I believe) article about keyboard latency[1] and it all started to make sense. I switched to native keyboards and never looked back.
In case you're wondering what's my typing speed - I was wondering too and finished some random web based typing test which told me I'm peaking at 160WPM.