My husband and I saw three shows while in Vegas (I'm pregnant so it wasn't a crazy Vegas trip). We saw Transiberian Orchestra and LOVE by Cirque du Soleil and this was the best money spent. Don't spend the extra money to sit in the first set of seats on the floor because the mezzanine seating was better because it was stadium seating and therefor, there weren't any heads directly in front of you. We bought tickets on travelzoo and got a free upgrade to the front row of the mezzanine, which was perfect.
As for the show, the actors can really sing and I can see why the show is currently the best in Vegas. It's upbeat and I didn't realize that the Four Seasons even sang all of those classic hits. Tickets are half the price of a Cirque show, so check it out and you won't be disappointed!
On a side note, I wouldn't take children to this due to language throughout the show. F bombs were dropped pretty consistently since the boys in the story are supposed to be Italian street kids from Jersey.