Well, ok. I just spent the last 10 hours checking out the Cats and Dogs EP (my eyes are now a bit buggy... lol). And so far this is my opinion.....
Adding a dog or a cat to your family is the equivalent to having Cassandra Goth spend the weekend.... with the exception that you don't have to put a leash on Cassandra and walk her to the bathroom. (However, she'll still need a cat box in the form of a toilet)
The dog(s), and cat(s) are NPC's.... just like Cassandra. But with both (pets vs Cassandra) you can interact, and do things with.... such as play games. With the dog you can play ball. With the cat you can play laser tag. And with Cassandra, you can play video games.
Sometimes Cassandra may leave and go back to her home. Sometimes, the cat will run away. Maybe the cat goes to Cassandra's (don't know).
The dogs and cats can communicate with you if you ask them what's wrong. Plus their animations can be tell-tale signs of what they would like. Cassandra can knock on your front door to tell you she wants to visit, and she can call you on the phone and invite you to her house, or a party.
You can have relationships with your pets (become friends). You can mess around with Cassandra on the couch.
Maybe it's just me but, Cassandra seems to be much more fun than those cats and dogs.
