Personally, I don't find many gigs impressive...and I go to quite a lot. However, I can honestly say this is one of the best gigs I've ever been to.
The band played great, the songs are great and very well arranged, the ensemble were good and the venue is just the right size (and had a great atmosphere). I found the brass section to work particularly well. I also liked the fact that the band just enjoyed playing the songs and didn't try to put on a contrived performance which so many bands do.
Overall, I don't give anything 10 out of 10 but I fail to see how this gig could have been better. Maybe the toilets could have been nicer?