Of all the reviews on the internet only two products have high ratings not only for usability but also effectiveness. This is Novartis Capstar and Bayer Advantage for Cats. Most of the other tick and flea products don’t get very good reviews, even as these two products do have their detractors.
Every pet is different and you will need to speak to your vet about which products to use on your cat or dog. The oral tablet is effective as you will see results after an hour or so when the fleas twist and turn before they die. Since it might not going to kill the egg stage of the flea cycle you will need to administer it again later to take care of the last fleas. Note that the smallest animal is a 0.5Kg dog and nothing smaller than this.
It is always best to speak to your local vet about tick and flea control on small animals as most of the negative reviews had been its usage on puppies and not so much adult dogs. Always take care as to what medication you give your animals and always take advice from a vet before usage.