Well, I've been using 10074 since a day or two after release...upgraded from 8.1 to 10072(?), then to 10074. It took two tries to do the final upgrade, and the whole process was super-slow, took several hours. This message is just a snapshot of where I'm at.
10074 has been pretty solid. There have been glitches, but nothing deal-breaking. For a while I had the Photo background process eating processor cycles like mad. There have been a few instances where I had problems coming out of standby, but they didn't require reboots. I haven't used Cortana at all, and Edge only enough to know that it works. Chrome is my primary browser and it works just fine.
One thing I absolutely love is the ability to easily turn display size up to 200%. I don't use any peripheral devices with my SP3, except a mouse now and then (and not since moving to Win10 this last time) and external disks/USB drives, so I don't worry about external displays and any resolution problems associated with them.
Most of my apps work fine...Office 365, Chrome, Scrivener, NotePad++. I don't understand how the new Photo app works, I guess it's still too much in preview mode. I can see my pictures, but I don't see any way of controlling how they are grouped, put into albums, etc.
At this point I don't see any reason for me to revert back to 8.1, as I've done a couple of times since October. I can't say I like Win10 as well as I've liked 8.1, but it certainly works well enough, and I'll get used to it.