Pros: thermostat controlled, it will only heat when a cat is inside. Machine washable!
Cons: you do have to plug it in.
I bought this for the Rogue when he was diagnosed with moderate anemia. He spent some time in there when he was sick, and I hope it gave him some relief from pain. These come in two sizes, 20 or 16 inch, and I had the large one for the Rogue - the Rogue was huge, but there was still space for someone else to snuggle.
I bought the small one for Sassy Josephine who likes warm places. She usually sits on the hood of my car when it is still warm. She loves this bed! And the best thing: the heating pad can be pulled out and the entire bed can be washed in the machine in the delicate cycle.