1. Nether I or my friend was able to get the PTY airport WiFi working. After the initial screen that asks for name, last name, nationality, email address, and a checkbox to agree to terms and conditions, the users are redirected to tocumenfree.tocumenpanama.aero website, which never loads, and the Internet access never activates.
2. There are no arrival information monitors on the air side. My plane was diverted, and with no Internet and no information my friend was in the dark as to what happened until she got outside. We were planning to meet inside.
3. Spanish language is definitely needed.
4. McDonalds, hotels, Super 99 grocery store, and some bigger stores (such as El Costo, Primor Internacional, Titan, Sportline America) do accept American Express. But smaller stores and restaurants do not, in my experience.
5. I was impressed with Metro. Did not try the busses. Taxi and Uber work fine, though I was unable to change the phone number in my Uber account from the US number to the Panamanian number. As such after requesting a ride I had to dial the driver myself to confirm pickup location.
6. The rain through my stay was absolutely not an issue.
7. Loved the islands, the food, and the scenery.