I haven't used it yet, however I wouldn't expect significant changes to the wait times. The digital queue still requires you to be on-property (or close by) so it won't get worse with people joining the list from all over Disney World, but that also means likely the same number of people that now walk up to the kiosk to drop their names will be using this system. The earlier hours may help relieve things a little, but logging in at 3pm, you're likely going to see the same times you would when you went to the kiosk - which will be dependent on when you are there and crowd levels and such.
It's the same system as the other digital waitlists - so it will give you a time to return, likely a short window like 10-15 minutes as it will assume you stayed nearby - you might be risking it to head off to a park and hope you get back in time. I hope to be using it in early February when I'm back there.