We've been here since Friday and stay till Sunday. Here are my thoughts so far.
1) I was very paranoid about COVID and almost canceled this trip. Like, we hadn't really left the house other than work and a few runs for urgent groceries since 3/13. Getting here felt weird but good. We quickly acclimated to the Disney bubble for better or for worse, and now I'm not sure how to go back to reality. Do we eat in restaurants when we get home? I don't think so, but being here has somehow shifted my brain a bit so that I've kind of forgotten how worried we were. I'm not sure that's a good thing, but it doesn't take too long to feel more comfortable and assume Disney and the other guests are protecting you. It's very much a false sense of security if I'm being honest, but I think if you're going to enjoy your trip it may be that you have to assume the best of people and hope that the virus levels in the park are minimal. You will spend time closer to people than you have at home, and there's no way to avoid this. If you don't like that, now isn't the time to come.
2) That all said, I do think compliance with the rules is generally good. We have seen probably 95% mask compliance. It's very slightly worse at the hottest times of the day and then later evening at DS and EPCOT. My assumption is that by the end of the day people are either tired or have had some alcohol and their judgment isn't as good so they get more lax. Most of the time it's easy to avoid people because the crowds aren't much. But sometimes you get stuck in line with a group that clearly doesn't care and you just figure out how to stay a few more lines on the floor away from them.
3) The masks haven't bothered us nearly as much as the heat. Mask or not, it's hot. We have been unable to avoid drinking in line - there were a few times I felt like I might pass out and having some water was the only thing that saved me. We, and most people, do it in a safe-ish way, ie quick lift of the mask while facing away from people and staying back an extra line. It's just impossible not to with so many queues in the hot sun beyond the ride queue starts. Overall I don't think people are abusing this, mostly just trying to survive.
4) It's peaceful here. People have generally been friendly and excited to be back, and the usual arguments between families and such are at a minimum. CMs seem more wonderful than usual. We've had some great service all around.
5) Transportation is dodgy. When it works it's great - they do a good job separating people on buses and such. But if Skyliner is down, or they aren't sending enough buses for Pop, it's more frustrating than usual. The longest lines we've waited in have been for buses hands down.
6) Ride lines are great on the weekdays. The weekend was much busier as others have said. We love FP and rarely wait for rides, but overall we've felt like we've been able to do what we wanted and a decent pace. Getting in before rope drop is key, especially at HS. Plan to start early especially with the heat.
7) We brought extra trash bags for our room and ordered groceries. Both things have very much helped avoiding the morning rush for breakfast at Pop and keeping our room somewhat clean with limited housekeeping. I don't think I'd pay for housekeeping if I had it to do over. They are doing the bare minimum and we've had to call for a broom and extra towels.
8) I brought a bottle of detergent and some suction cup hooks for the mirror. Washing out the masks at night and hanging them to dry has worked well.
If you're a Disney fanatic and healthy, come. You'll have a great time. If you expect perfection and full service everything, or you have health risks or are really worried about getting sick, wait a bit. It's still very magical, and CMs are doing a great job, but it's not the same as normal. We've enjoyed it and have no regrets, but it is a very different trip than we're used to. We miss park hopping the most, and not having things to do early morning and later at night as we like full days. That said it's been relaxing too. Let me know if you have any questions!