What are the side-effects of downloading/updating Windows OS from Windows Insider ?
- you get new features faster
- You can provide feedback to MSFT on what you would like to be modified
- less stability - it is BETA or ALPHA quality
- You get "spammed" by MSFT in some cases asking for actions, comments or to attend webinars
So if you are fairly technical and can deal with some features not working 100% and enjoy testing new areas go for it.
If you are a regular user, stay away or you may get frustrated