Due to an unusual circumstance. I found myself near my 4GB limit just a few days before the 5GB upgrade kicks in. I decided to push the limit and see what happens.
I crossed the boundary while playing a video, it choked. I received a text message that looked like it might be saying my rate was being throttled. It looked semi-gibberishy.
Having done that, I ran some tests. Video, forget it, YouTubes lowest resolution is still too much for that data rate. Audio streaming: I tend to use low bitrate streams, and they mostly worked, but would gap out now and then. E-mail, since this is message-based, there is no real perception of slowness unless I watch for the messages to send. The client tells me when messages are downloaded, so I’m not aware of any slowness in receiving mail.
Web pages, for basic news pages and such without video, are a little slow, but not enough to bother me. The delay is primarily in the images. Navigation, I use Waze. Trip setup is definitely slow., Once moving, there is no perceivable lag. Slow startup is a minor irritant to me, but endurable. I’m not sure what would happen with a voice chat app, I’m not going to bother anyone just to test that and my data renews tomorrow. I tried the mobile key feature on the Marriot Bonvoy app, it opened my room door.
Based on this admittedly limited testing, it would seem that only apps that seriously chew data will have significant degradation. Most other apps should function seamlessly, if a bit slower than usual.