Besides not having to get up to switch disks there isn't much. If your PS3 gets stolen your physical games probably will too but with digital you can re-download them onto a new ps3 should you get a new one. Of course the risk here is that this is only available so long as PSN is up. Once it goes down you get hammered as you can't make a back up and put it on a new ps3 should your old one break or be stolen.
Physical is the way to go unless you have a high chance of being robbed.