I think one of the advantages is being able to state your arrival time. Not sure if it actually works this way, but if you arrive early, I like to think it gives them a better chance of assigning you to a room that might be available when you get there. Plus they text your room number to you so you can go straight there if you prefer to skip the lobby. One downside is you don't get the front desk experience which I actually kind of enjoy. When we last did it, we still went downstairs to get park maps, a resort map and buttons, etc.