Hi, I can only compare with FP3 but the FP5 camera is really very much improved. It’s probably still not a phone you would buy because of the amazing camera, but it’s very serviceable and the low light pics it takes are very decent. I no longer feel the need to ask others to take pictures because my own would look like they were made with a potato.
Here’s a huge thread with pics from the FP5: FP5 - Pictures Gallery - #28 by HolosericaCaligo