I was in Sapphire Lounge PHX on opening day. Plus side - Everyone was friendly and helpful, and a few offerings were outstanding - like the roast cauliflower from the airstream. They're really trying hard.
Downside - it's very small, and while they're trying, there are major traffic flow issues because they've got too much in too small a space. The airstream is really cute, but takes too much space, and there's no room for a line for ordering. Also, one has to walk down a passageway past the bar, then do a u-turn to the left to get back to the airstream. Once in that patio wing, you can either exit the cumbersome way you came in, or slip out the other way, which is technically before the registration desk where you enter, so you're basically outside the lounge unless you weave back the way you came. I was fortunate - there was no wait. That won't last, and we're all on limited time during our connections.
Removing the airstream and opening the area up for more seating, just serving the food offerings all at the buffet tables, would be a wiser design choice. Not as cute, but practical enough to accomodate more customers. It would also help if they did't take custom orders for the airstream foods. Just premake it and set it on the counter. Wait for food was very long, as it was just one or two people making it all to order. Not practical for an airport lounge.
I got the Reserve card because I'm through Phoenix regularly. So I paid for the reserve for a long time before the lounge was open, and now that it is open, I can't see getting a lot of benefit from it because it's always going to have a long line. Food offerings are also very limited, as expected from a lounge this small, but that decreases the value of lounge access. I chose the Reserve card because of 3 new lounges coming, including PHX, since the card is so much cheaper than AMEX. But I'm questioning that decision. May drop Reserve and pay the ridiculous fee for AMEX, as they have lounges everywhere and the Sapphire lounges I will be able to access (not being a New Yorker) don't quite measure up, from what I can see - not worth the extra price of the Reserve card.