Well, I went last night, and had an absolute blast...thanks to slimz for the very helpful tip on tickets still being available. I'll try to do a report as best I can...as usual, it will be choppy and random.
Got Dang it, Rusty !
I was waving at you and you just ignored me.

Actually, with the mass of folks, you probably thought I was waving at Garth and/or Trisha. They certainly waved at me...

Mrs. cyclist's company had a suite. Let me tell you, that was sweet (pun intended). It's been years since I've been to a concert, and this was a lot of fun.
And I did enjoy Trisha's part, but it wasn't her best work at all. She can really belt out the songs. Her following is more niche, obviously. And like everyone has said, Garth has a great bond with the audience. His voice was kinda going, but it didn't matter as the audience was singing along anyway.
Oh, and it's going to be a great arena for basketball, hockey, etc.