Summoned creatures have their limitations. They are normal animals, so are subject to the normal desires of any animal. They can tire, and need food and drink to survive. They must find their own way to the vampire's location, and the time it takes for them to arrive depends on where the vampire is. However, a group of cats would be there in an instant.
Lycanthropes are immune to a vampire's summons.
A vampire must issue short, easily understood commands. Communication between the vampire and animal is not guaranteed, as the animal will only get the general gist of the command. Success means that the animals stop what they're doing and return back to where they came from. Failure means the animals continue what they were doing. Attempting to wrest control of the animals is not an instantaneous thing.