I tried to be a good boy and leave it on, but it suffers from the same nag crap the last version had.
At every login after about 15 or 20min it warns me it needs to scan. Without a reboot every day it warns me of needing to scan
at least 1 to 2 times a day. I nuked it today and removed it R.I.P Defender

EDIT
With real time protection on, and scans scheduled in Task Scheduler for daily scans these irritating messages should not appear, but they do.
MS fixes that and I will give it a go later on down the road.