I think it's actually good as the Philippine Basketball Association (PBA) made them an official partner. That adds to their credibility. I have a Paymaya account myself, just the other day and was able to create my own virtual card which I can top-up using different stores like 7/11, Smart Padala, Cebuana and many more. You can even earn bonus money if you refer a friend to use it, which I think was 50 php.
Regarding your paypal inquiry, I have viewed a video in youtube saying it can really accept paypal funds. You just need to link your Paymaya card to Paypal. But before linking, you need to load your Paymaya the amount of 150 php so that paypal would confirm the linking. Don't worry, that will be refunded a day or two after. But if you withdraw funds from paypal to paymaya, there is a 200 php fee to be paid. I don't know if the promo 80% off is still going on because I have not tried yet.
Well that's all about paymaya as far as I know.