The biggest issue so far seems to a missing power management drives from Lenovo, which cause my computer to freeze when it shuts down.
I downloaded build 10041 from Microsoft, and updated it to build 10061 through windows update, which was a fast and smooth process. The fact that Microsoft now releases new builds through Windows Update is something I really like. Maybe we will see them release new OS versions this way in the future.
Windows 10 Technical Preview