If you are already enrolled to “Preview for Developers“, it is totally fine to become a Windows Insider as there are known risks or irritants. The Builds you will receive are internally tested and Microsoft won’t release something that will break your device. Though you can face similar bugs that you may have faced with Windows Phone 8.1 preview builds. I can confirm this being a “Windows Insider” for Windows 10 desktop preview, since the time it was launched.
In case, you are totally new to this “Windows Insider” or “preview for developers” thingy, you should know certain things before taking the plunge,
1) Bugs (Lots of them) may mar your experience.
2) Windows 10 for Phones initial preview Builds miss some features as compared to Windows Phone 8.1 latest builds. Check to make sure you can live with that. Click here.
3) This is the only way to receive the latest Windows 10 builds before official release later this year.
4) Preview for developers and Windows Insider (Windows 10 Desktop) experience for us has been relatively smoother, so if you ask, we recommend to go for it. But read point 1, 2 and 3 before making any decision.