It actually sounds like it should be fun, if you’re a Sims fan. But the splicing of these two ideas comes at the cost of any real depth. While you do need to worry about things like telling your Sim to go to the bathroom, feeding him or her, and taking their dog or cat for a walk, etc, your interaction options are actually quite limited.
The same goes for the vet setup. Each pet will suffer from one of about five afflictions, and diagnosing them is only a case of grooming them, using a stethoscope or running them under an X-Ray until the game tells you what’s wrong. Apply the proper medicine or bandage, and you’re done. The whole thing gets old by about the third in-game day.