Hello,
HZPiano I'm currently downloading it and if there is anything interesting to say about it, I will jot a few impressions here.
In short: I tried it and then swiftly uninstalled and deleted it.
Currently, Soundpaint is public beta software comprising of a free proprietary engine with a free piano library as a sort of 'starter pack' into their new Soundpaint realm. Further instrument and/or effects additions are individually paid purchases. The ideas behind this small company are amiable, as it seems.
If you just want to mock around with some audio software technologies, well, you can.
If you are even half-serious about piano playing, it is completely unusable, with a sub-sub par sound and lacking virtually all adjustments and for instance pedaling options we need and love in our proper virtual piano libraries.
If you like a sound leaning towards the synthetic, you are much better off with Pianoteq.
If you are after the best approximations of a full, rich, authentic piano sound and behavior, and much-needed playability and adjustability, like me, then all of us here know where to turn to.
For me, the top-two are VI Labs' Modern U (my daily lovely study piano) and VSL's Blüthner 1895 (which will still have to remain on my wish list for some time to come).
As a final thought: I keep being amazed how virtual instruments can be presented online as amazing and great sounding, while they actually are…
Cheers and happy healthy purchase*) decisions,
HZ
*) This one is a free download, but anyway.