I flew out of the new concourse this morning. Can confirm what others have observed-- it's nice. The first thing that you notice walking into the concourse is how quiet it is. They have selected materials throughout the concourse to absorb sound. Not a library by any means, but it was wonderful. No announcements at all other than boarding announcements in the actual gate vicinity (never could figure out why you need to be reminded that TSA limits the size of liquids to be taken through the checkpoint, while in the bathroom post-security). A lot of deplaning passengers were not prepared for the new concourse and were shocked based on their expectation of LGA.

My only negative observation was that the bathroom (which was also nice) was not big enough. At the end of the concourse that's currently in heavy use, there was a line for both urinals and stalls in the men's room. On the one hand, not surprising, given that there were 3x WN 737, AC A320, a couple of E75s and an ERJ all parked on that end of the concourse at once. On the other hand, it's surprising there isn't more capacity given that it's a brand new building and not all the gates are even in use yet. On the other side where the gates are not all open yet, there was another men's room that was less busy, but it only had 3 urinals. I'd still rather be in this concourse than in any other NYC area airport terminal, but it seems like a potential oversight.