Windows 10 Technical Preview for phones

I test Windows 10 for PC since weeks, but I had no device available to test the phone version. As I just changed my Lumia Lumia 625 for a Lumia 1320, I could not wait to test Windows 10 on the Lumia 625.
How to install it:

• First, you need a compatible smartphone: http://windows.microsoft.com/fr-fr/windows/preview-supported-phones
•  I recommend using a different phone than your primary phone because the system is not yet stable.
•  Register your Microsoft account in the program "Windows Insider" here: https://insider.windows.com/
•  Download "Windows Insider" application from the store or here: http://windows.microsoft.com/fr-fr/windows/preview-download-phone
•   Run "Windows Insider" application . Two operating modes are available for this application: Slow = more or less stable version or Fast = latest version with more bugs. For my Lumia 625 only the Fast option is working.
• Then go to the Update menu "Settings / Phone Update /check availability of updates"
• Install the update
• The phone reboots by installing the update.

Note that this is an update and not a complete reinstallation. The parameters and programs should normally be preserved. Unfortunately, in my case, the main menu was totally unstable. I was able to make it usable by resetting from the menu "Settings / System / About / Reset your phone." It then was reinstalled with a clean system while remaining in Windows 10.
 
Honestly, this system does not upset much compared to Windows 8.1. The most notable changes i see are in the settings menu that sound much more orderly and understandable than the old.