I'm sure there will be kinks to work out. Especially people needing to know that they need to fill out the online form.
I saw a post on Facebook where the arrivals hall was completely full of people (probably around 2 in the afternoon) and they were complaining about the system. In this case, I am betting it is a lot of people needing to know they need to fill out the online form as well as the system not working completely correctly.
Airlines could do a lot to help that. Since we all need to arrive several hours before leaving, many people could be filling out their forms (if they haven't already) while waiting to board the plane!