After having Win10 installed on my laptop for several weeks now. I find it works well and is in general more responsive than Win7, and seems to work well with Sonar.
My only real issue, with regards to audio production, being I cannot reduce the memory usage at boot up to less than 35%. I've tried turning off everything that I can think of, Win7 used to settle at 32% for me, and that extra 3% does make a difference on a 32bit install where the actual available memory is something just over 3GB. There are one or two projects that I've had to reduce the number of VST's just so I can keep working on them.
I find the implementation of settings, and where and how to find and adjust them, a little clumsy. I think this may have something to do with Microsoft trying to make Win10 a one-stop OS for all devices. In doing so it seems that some things are not in an obvious place, or are in more than one place, for either a full blown desktop setup, a laptop/tablet, or a smart phone install. It may be a minor thing for someone more well versed in the intricacies of computer workings, but for me it's just a distraction, and I find myself spending a lot more time than I would prefer, searching for certain settings that were a little easier to find in Win7.
I will persevere with the Win10 install on my laptop, as it seems both Microsoft and Sonar are trying to make this a better way of working with audio. I applaud them (mostly Sonar) for trying.