Better than The Sims 2 Pets and hey, horses are great!
Also stray animals are not as annoying as before. Now you are able to control pets, which some people may dislike but it's for the better. And you even got traits for pets, which make them more unique! The Create A Pet tool is quite amazing, with some very advanced options, so you should be able to create most real pets in the game.
This is probably the best expansion pack for this generation of The Sims and one of the best ever. If you like The Sims at all, you should try this.