Another vote for favorite here. We eat at Concourse every year and are sorry it will be closed in September. As for the other question, yes, you do need to make ADRs.
We just ate there in October and it was the best meal we have ever had in WDW. The teriyaki wings for the appetizer were fantastic and the ribeye was excellent. I was so sorry to hear it is closing because I'd hoped for us to go there again this Sept. I would highly recommend it!