I walk a dog that loves frisbees and the aerobie is without a doubt a favourite.
Lightweight, easy to throw, travels a long way (even when you are rubbish at throwing) and great fun for dogs.. and quite fun for owner.
Only downside is that playing tuggy with a frisbee or leaving the dog for a couple of seconds unattended does end up with a punctured, soon to be broken frisbee, but I cannot fault the maker for this as it is not designed as a dog toy.
Also a shame it doesn't float (both for people and dogs).
Finally its a bit frustrating when you get them stuck in trees.
Despite all this we keep buying them!