I'm debating that same issue. I like them and my dogs would probably love riding in one, but I don't know of anywhere I would use it...let alone bring myself to use one. (no offense to anyone that has one)
In my area it would just seem weird to people since everyone is out
walking their dogs and pushing skin kids in strollers. However, I am looking into getting a caboose for dogs that attaches to your bike. I think the basket would be too small for both of them. That type of thing I would use.