Not really, other than the current build (10512) not having mobile hotspot (internet sharing) working, which is a "major" issue for some people that rely on this function for their internet connection on other devices. Other than that, there are just a few things that they're still working on here and there. Some functions that you may be used to with 8.1 might be missing, or in a different place now.. A few bugs here and there, but it's nice and stable and good for daily use in my opinion. I've been running the Win10 Insider Preview for a while now without any issues.
Edit: a new build is expected to be released soon (like this coming week) and is reported to have the mobile hotspot fixed and back up and running, so if you depend on this feature, you may want to wait until this new build gets released.