I went last Saturday, getting our rush tickets at 4 p.m. for an 8 p.m. show. Our seats were in Row U in the orchestra on the left side. We seemed to be surrounded by TodayTix purchasers. They were good seats. The theater was not full. I make no promises for what you would get, of course. It looks more crowded on Labor Day weekend (although there are plenty of tickets Friday as of now).
As for the show, the main performances are fine. I hadn't seen it before, and admittedly have a bias against jukebox musicals. This one had the usual problems with the book, as it ended up making Carole King - whose accomplishments are even more impressive than I realized - less interesting than the actual person must have been during her career. The "Will You Love Me Tomorrow" section, which illustrates the creative process and shows how talented she was at such a young age, was the highlight of the musical. I was bummed when it devolved into a steady diet of hits. Still, as my wife commented, it was pleasant.