I am now using build 10041. I installed it the first day it came out so have had the chance to use it quite a bit, again this is my main laptop. I am on the fast ring or updates.
First thing to not is that mail, people and calendar break. One has to go through a little hack to get this working: took me a few hours to get that working. Well… still technical preview so no complaints.
Some new features are exposed and I like that my wireless connections seem to come back a bit faster than they used to on the previous build, I also like the UI for that – matching the actions center.
All in all seems more stable that previous build and works very well.
My biggest issue is with app scaling. For some reason my modern apps do not scale well. I have read of others with this issue as well. It makes some apps basically unusable. I use the mail app alot and I am not able to see all my accounts in there because the go outside the window of the app (even in full screen). I have tried different app scaling options as well as different resolutions but none seems to work.