wireless connectivity anywhere will vary based on how many people are connected to each wireless device, the types of devices and what services they are using (email, streaming, etc). since its shared bandwidth per access point (a wireless network consists of many throughout a building), you could have a different experience every day of your trip or even at different times of the day. this is why you will see some people say wireless is good and others say its horrible. this is not a problem specific to disney.
my responses to the surveys has been to either charge for wireless (which they won't now that FP+ appears to have a smartphone component) or block high bandwidth sites like Netflix, Hulu, etc. While these would help with the bandwidth issues, they would generate a whole new set of complaints.