This is a good expansion pack, which actually adds enjoyment to the game. It is an improvement on the old Sims 2 Pets pack for several reasons. Firstly in addition to customising the look of your pet, you can now customise their accessories and choose from a wider range of character traits. With this pack you can also now actually play as your pet, and are able to fully control their actions and interactions. Your pet now has it's own wishes you can attempt to fulfil to gain "Lifetime Happiness" points.
The best feature of all is the addition of horses. You can ride, train and groom your horse, buy equestrian goods (including different types of jumps), and can even become a "jockey". There is also a lot more new actions, interactions and training features available with the other pets, and new lifetime wishes for your human sims.
In addition to the horses, dogs and cats, you can also collect birds, snakes, lizards and even turtles.
There is a new town full of special "pet features" and if you go the collections section of the Build Menu, you'll find a new Sims 3 Pets collection of building & decor features, pet related goods and furnishings.
There is no instruction manual included in the game box, but you have the option of using the in-game tutorial if you need it, though if you're used to playing the Sims you should be able to work it out as you go along.
So it's a good pack and definitely worth buying if you're a fan of the Sims.