I made sure I had a copy as soon as it came out, and I'm listening to it now.
Almost anything using Beatles recordings as its source is bound to be worth a listen, and I'd say this is well worth giving a try. A "mash-up" is a recording taking pieces from different songs and putting them together. So you may hear the lyrics of one song over the instruments of another, a "medley" of songs, etc.
It's very inventive, and well done. "Old" songs are given a fresh perspective. This does not sound to me like a cheap, classless "cash-in," although I expect some to level the charge. I'm glad it was made, and glad I bought it!
I hesitate to give it the "top" rating, though, as it IS really a soundtrack and perhaps not really meant to be listened to as a stand-alone work. I can see listening to it as "background" music while doing chores, paying bills, etc. rather than something I would sit and listen to carefully over and over. I hope a DVD of the Cirque de Soleil (sp?) performance, with soundtrack, is released. THAT would be the "complete" work, and apparently the way the songs were originally intended to be heard.