OK I bit the bullet and got this.
First impressions are not good. It seems to have only ONE sample layer and relies on filtering to give the impression of timbre change. Very disappointing really - the over-filtering actually causes some notes to sound softer the harder you play!
So while a single note sounds quite pleasant the playing experience is not nice at all. Its also way too easy to let a finger slip onto a note ever-so-slightly but it rings out as loud as everything else.
The only +1 I can give it at this stage is the impressive low latency and high polyphony.
The maker of this app needs to do a lot more work to address these issues before it should be taken seriously by musicians.
My honest (and unbiased as humanly possible) ranking of iOS pianos is:
8/10 Free Salamander played on bs-16i app (free from my site)
7/10 Rich Upright in iGrand (requires a second purchase)
6/10 Ravanscroft 275
5/10 Korg Module with Ivory Expansion
4/10 Colossus Red Japanese Grand (has latency issues - I don't have the huge 14gb Concert Grand)
Best to save your money at this stage.