I was at SSR from Nov 11-20, and the wifi was terrible in the room. The wifi was slow and froze often, forcing me to to reboot my tablet frequently (every 5-10 minutes or so). This was true in the morning, afternoon, and evening, so I wouldn't blame it on higher demand at specific times of the day.
On my last day I had a few hours to kill before Magical Express, so I was in the main SSR building in the afternoon, and the wifi was actually usable. It was amazing how much better it was (no freezing, I never had to reboot).
Disclaimers:
1 - SSR is huge and very spread out, so I suppose it could have been better in some areas than others. My room was in the Carousel area, far from the main lobby building.
2 - A friend who was with me for 3 days at the beginning of the trip told me she didn't have issues with the wifi, and she was using a laptop.