First of all, let me say it's wonderful to finally have this in hand! Kudos to the Mac team at PG Music for finally making it happen!
A couple of things make me wonder if they pushed a little too fast, however.
The Audio Chord Wizard doesn't work: can't launch from within BIAB and the stand-alone version, while it recognises chords fine, will not export them to BIAB. A patch is due in a couple of weeks, but I thought the most basic beta testing would have caught this.
The style picker is much improved in terms of layout, but has the same bug that the 2006 version had (odd, if this is a "complete rewrite"). After previewing a number of styles without exiting the dialog, the font suddenly switches to 9-point Geneva (Arial?). Cosmetic, true, but it shouldn't do this. Also the Cancel button still does not restore the original style - it effectively works the same as the OK button. Not helpful.
The manual I got with my upgrade order is essentially an extensive addendum to the original 2006 manual. The program is now big and complex enough that a whole new manual is in order, so that all the information I need is in one place.
Finally, while I was moving all my zillions of styles over from 2006, I inadvertently renamed a few of the style database files as .LS3, with the result that BIAB tried to read them and update its style DB. Being unable to parse them (they weren't really .LS3 files) it simply crashed. Some error-checking and a message would be nice.