Pets are more enjoyable virtually.
The new creature added in this expansion is the furry night-dweller, a werewolf. Your Sims transforms into a werewolf at 8 PM every single night, so you should probably get a day job instead of a night one.
You can own lovable cats and dogs, even birds and hamsters. This game is addictive and grows on you, because at first your like "weren't they supposed to include pets automatically?". Yes maybe they were but just forgot, though that doesn't make this game less enjoyable.
Overall this game is worth the money you have to spend on it, and if your a Sim collector like I am, then it will do you good to get this expansion. Enjoy training the pets!