We liked it and had previously used old FP on a summer trip. First trip was late July, which isn't exactly a low crowd time. I think I got 4 or 5 additional FP+ for our 3 day trip. There weren't kiosks at the time. You had to talk with a CM holding a tablet. A couple of times, MK I think, I just walked right up. We waited 10 minutes or less at AK. The longest wait was about 15 minutes, and I got an FP+ for Buzz for an immediate time. Waits for Buzz were 20-30 minutes then. I don't know if the kiosks are faster than the CMs. Plus, there are fewer kiosk spots than there were spots with CMs in the summer.
We rode 5 rides at Epcot before noon, including Soarin' twice (1 FP+, 1 SB), and child swap on Test Track. It was an AM EMH day, and we were there at RD. We got to AK between 2-3pm and rode 3 rides, including Safari with no FP, and watched Flights of Wonder. We had to wait out some really bad rain too. We left the park before 6pm. At MK, we rode at least 10 individual rides (SM twice, Buzz twice, Tiki Room 3 times, POTC broke down twice with long waits even in FP line) did Tom Sawyer Island, ate lunch at BOG, and watched the parade and fireworks. We got there a little after RD with AM EMH and stayed until closing. We had 3 prebooked FP+ and 2-3 additional ones at MK. So, we definitely rode more than 3-4 rides per day, even during the summer.