The latest build is now available - build 10041. If you have elected for fast updates it is coming via Windows update, with a slightly odd name; look for "10041" in the update list. I have it installed on one machine. Haven't had a chance to really look at it, but my first impression is that it is a bit faster. IE hung up on me though. It also looks like the double login avatar has disappeared.
On the other machine I haven't been able to install it because it is failing to complete an update that is earlier in the list - a driver update for a "high definition audio device". I can't find a way in Win10 to bypass individual updates - anyone got any ideas?