Yes, the YMW820 chip that is inside this gadget is a complete GM synth, including effects !
I got it by amazon.com and received it two days ago.
As far as i understand, the custom phoneme/sentences need some MIDI sysex.
Note that the sound quality is not great, there is a permanent digital hum on the audio output and speaker (even when running on batteries without USB connected). Maybe it can be fixed by adding some capacitors and shielding... i will give it a try.