Installed this on my Nokia Lumia 928 last night and it has some problems. The most notable problem is it still has the battery drain issue. With this W10M build on my Lumia 928 I don't even get a full day before the battery is completely drained from a 100% charge, and that's not using the phone much at all. When running Windows Phone 8.1 on this same device I easily get almost two full days, with regular use, before I had to charge the phone again. I've had my device reboot once, lock up, and the delay on taking pictures is pretty bad. There are still some issue with Outlook, like giving a letter/number combination for your e-mail account name, instead of showing the e-mail account name. What does work, however, works really well! The UI and animations like the transition to an app from the start screen are very smooth. All in all this build is definitely headed toward it's RTM goal, it's just not there yet.