Microsoft is increasingly fine-tuning its plans for the Technical Preview of Windows 10 for phones. Due sometime this month, the early release software is testing internally at Microsoft, having gone beyond the tightly lipped Operating Systems Group (OSG) recently.

Microsoft's Joe Belfiore tweeted yesterday on some aspects of the initial tech preview including that there is a limited batch of phone models eligible for the update, support for 512 MB devices (including the Lumia 520) and plans still for a February release. Now, some internal data has confirmed at least some of the phones that Windows 10 for mobile is currently working on.

Presently, the HTC One (M8) for Windows, Lumia 1020, and Lumia 1520 are all being used internally by Microsoft to test Windows 10. Of course, this is not the full list of phones. The list is just a partial one of users who have identified their phones using the feedback system built into Windows 10 preview. As expected, the initial batch of phones eligible for the Windows 10 preview are likely to be newer and high-end e.g. Lumia 830, Lumia 930, etc.

This is the good news.

The bad news is more the obvious part: this is an early release, with plenty of bugs. Windows 10 preview for phones is not like the Preview for Developers Program with finalized builds for OEMs and carriers. Instead, this is beta software. Some of the bugs identified by users with the phone edition and using the Feedback app include:

WP10 seems to drain battery very fast, and it gets the device hot with simple things like phone calls

Animations are not smooth

HTC One M8 you cannot hide the on-screen buttons and they are above app bars and the keyboard

Glance screen does not work on WP10 (for HTC One, at least)

Quiet Hours turns alarms off

The point of Microsoft testing this release internally is to identify and fix these bugs as soon as possible, based on a priority system. As such, when Windows 10 for phones goes out to the public, some of these things may have been already fixed. Seeing how the sausage is made is not always pretty.

These (and other) bugs do raise the question though if you should install Windows 10 on your primary phone. At this time, the answer is looking a lot like the one for Windows 10 on PC meaning it is probably not a good idea, at least not the first round. Although the core of the OS is there, many bugs may make Windows 10's initial preview for phone a non-starter for some users.

Thanks, Jesse Leskinen, for the info!