I could do some extensive testing of the beta.
My impression at first was bad, a lot confused patches. so after resetting it lighened things up, was much better and so far I like, what it does to the playing. Feels and plays even more like a real amp, dynamics, response and the distortion/gain stages is great!
Clean Amps are really superb sounding!!
But... when playing, and also listening to clips others have posted, I feel like it sounds a little bit like a slight blanket over the speaker, missing a bit the "headroom" or "brilliance" in the hights...
Now I even tested it in my bandroom, in several configurations (PA, cab disabled over an amp&cab, Poweramp&cab disabled over a BGW Poweramp into cab), and it is a bit weird:
With "FRFR" and with the neutral Poweramp&guitarcab, there is this blanket-feeling, but when disabling the Poweramp-sim, it goes away. So I suppose, it has to do something in the PA-Sim?
17.04 (and also e.g. 16.04) didn't have this feeling for me, but only FW 15 had it also...
But as I said, it really is the only "negative" thing I hear/feel, otherwise it plays great!
So far, Congrats FAS