Just watched this in 4K HDR with Atmos. Overall, pretty great. I'm not a huge Chicago fan, but I respect the group and enjoy most of their recordings. I grew up in the 80s, so the pop hits are nostalgic. My favorite aspect of their music is probably the horn lines.
Excuse me while I get a bit nit-picky and critical...
The intro with drum solo and interview soundbytes was a little awkward - especially with the abrupt audio edit into the show's beginning. Immediately, I thought the drums sounded too loud and direct in the mix. That got a little better after the first song, but continued to distract me occasionally. Consistently, I thought the guitar solos and lead instrumentals were a bit low in the mix. The sax solo in Free was one of the few solos that "popped" appropriately for me. The mix sounded a bit "set it and forget it" while I would have preferred a little fader movement.
I thought the mix was generally pretty good and fun, just a tad unbalanced. I'd give it a 8/10. The resolution was certainly clear. The surrounds were subtle at first, but later brought in some percusssion and background vocals (that sounded a little artificial, but effective).
A few shots were slightly out of sync, but that was rare.
It seemed like the band was not playing to a click track, which makes me happy. If they were, they made it sound organic.
I enjoyed the guests for the most part. They are all obviously skilled performers. I was surprised how differently from the recordings If You Leave Me Now and Look Away were performed, considering they are some of the bigger hits. I wasn't really feeling Look Away, as the vocals had more of a joyful exhuberance that didn't quite match the tone of the message in my opinion. Voiceplay certainly got their own featured section for a while. It reminded me a bit of Bill Gaither-style gospel vocal groups... except, like, adult boy band or something.
Visually, it looked great. Some extra campfire flames and particle effects must have been added in post, I assume.
As a casual Chicago observer, I feel like I got a taste of the live experience and a decent sampling of their discography. I'm glad that they sold the Blu-ray separately at a reasonable price. It is well worth it. The songwriting, arranging, and performances are all world-class.