They have a great tone and can sound very realistic The Platinum version gives you Close & Room mics in addition to the Player mics in the Gold version. Each of the 4 pianos have a very distinct sound, although the Bosendorfer has a rounder, softer tone than the typical Bosendorfer 290 (eg. VSL Vienna Imperial or Galaxy Instruments Vienna Grand).
Playability is a real mixed bag. Despite the 18+ velocity layers, and their huge dynamic range (the FFF are great) in live playing notes will sometimes jump out with inconsistent tone or volume, particularly when transitioning from sustain pedal off to on. This can be fixed later via MIDI editing so it's not a huge problem for production work, but it can be annoying for live performance.
The big attraction for me of the EWQL pianos is their 'realness'. They captured a very full & resonant tone, and don't sound sterile & digital like many other sampled pianos. I have the Platinum version of all pianos, and mainly use the Bosendorfer & Bechstein, with a mix of the Close & Player mics. Occasionally use the New York Steinway D, and rarely the Yamaha C7 (which is a VERY bright 'Pop/Rock' sounding piano) unless I'm after that 80's Bruce Hornsby style brightness.