No real differences, except for problems with flash. WindowsCentral is distressingly unstable. Otherwise, it's about the same so far. I only have 4-5 hours of use on this build but I believe most of the changes were "under the hood" with no major features added in this build.
Cotana not working for me on Surface Book with this build. She will respond to "Hey Cortana" but just spins. My notebook and reminders wont load. I cant even get into settings through Cortana.