Far beyond any other piano instruments out there, and well worth the money (the Play version, which is scaled down for people who don't need so many controls and want to focus more on the music itself, costs €99 or about $130). Something I'll definitely get a lot of use out of, and already have; I threw out all my sampled pianos and such after getting this, saving disk space.

It's worth noting that there is one other physically-modelled piano software out there, 4Front's TruePianos. Having tried it before, I can say that Pianoteq is most certainly more realistic than it or any other piano I've used, sampled or otherwise (TruePianos, in particular, has an annoying tinny sound to the higher notes, which sounds very artificial).

Hats off to Modartt for this excellent piece of software.

The only true software piano simulator available. All other digital pianos are based on sample libraries, but this one is a physical model with no samples. The result is an instrument with real personality and greater responsiveness to touch. It's also highly configurable. I just wish it were cheaper, but even at the price it's a bargain compared to some of the high-end sampled instruments.