I have eaten there twice. The first time I just dropped by at lunch time with my wife. Normally, I refuse to wait at any restaurant for more than 15 minutes, but this time we waited for an hour. (Nice to be retired so that I don't hve to get back to work!) I thought that I would take my Mother-in-Law to eat there for her birthday and called for a reservation two days in advance. They only had one at 5:00 and one at 10:00.
I do believe that this PF Changs is smaller than the one in the Arboretium in Austin. However, I think that the issue is they will only take a few reservations an evening. That doesn't mean they are booked, it just means they don't like reservations.
Frankly, I don't think any place is worth waiting for an hour. I have decided to forego eating at PF Changs. You can walk into the one in Austin when you are there and not have to wait. We have plenty of good places in McAllen without putting up with the wait. If you want Chinese, the food at Dai Tung is pretty good, including no wait and reasonable prices.
If you want it, you can have my place in line at PF Changs.