I saw one a while back - seemed really inconvenient - the handhold is hard plastic and so it the housing for the leash part, so half the collar is hard plastic and the leash is too short to do much of anything with.
I have one that i picked up at a pet sale for $10.
I don't use it as a regular leash ever but when we are out in the fields or lake i sometimes use it. Its nice if i have to grab him quick and nice that i don't have to carry a leash with me.