Tried installing this on the kids PC's today... and removed it after a trial run.
1) wouldn't get updates - prob my WSUS server settings, etc
2) the main reason - If you click on Tools then Windows Defender Website - it opens up IE but COMPLETELEY UNRESTRICTED!!
IE is locked down tight by GPO's but Windows Defender removes this and they can get access to (and modify) Homepage, Proxy settings, etc, etc
Anyone else seen this or know how to resolve it?