Re: Which phone are you running Insider preview and how do you like it?
Build 10512 working great for me as well. Very happy about it. Lumia 920, hard reset (which means: no glance screen and that is a known issue for hard resets).
Why no glance? I believe (speculating) that glance screen will show up as a new option in settings in a future TP build or they will wait for the RTM. Right now, a hard reset simply does not install any old Windows Phone 8.1 code, I guess. It is not an issue itself since it is obsolete settings from WP 8.1, but as users we rely on it and expect it to be there, so Microsoft's down priority over it, is frustrating.
The lockscreen delay sure is annoying, but the things they did fix (phone calls freezing!) and performance things were great. They had more than 2000 fixes were mad between 10166 and this release. That is substantial. They say the next build will not take a month. That said, I expect the next build somewhere around 25-28 August. That is a number taken from nowhere, but it would make sense if they are going to return to normal release cycles. Let's hope the delayed lockscreen is fixed and that they keep tweaking the performance and stability, plus adding the Glance screen as a new settings option, replacing the old-fashioned Nokia Glance Screen WP 8.1 setting.