Bachus, come on!.. It has "Natural! Grand Piano" which is to my knowledge more advanced than any piano voice that any PSR has and as I see it any demo of DGX-650/660 shows that the piano voice is actually quite beautiful. Also it does seem to be well-priced, it's not that much more expensive than Yamaha's portable pianos like p-125 without any extra functions, so this product seems to be a real hit.
Its less advanced then all the Yamaha P series.
And there is no cheaper 88 key then this in the Yamaha assortment
Keep in mind, that this all says nothing about the quallity, just about the price... and that everything else from Yamaha is even better...