As an American, there's a hint of glory/patriotism about the PT boats, and a quick survey of other countries shows they all had torpedo boats, though of different sizes and configuration with a good degree of difference from the US ones. Did we use ours differently? Who else was a prominent user?
Lots of countries during the war used torpedo boats although the most well known are the Elco boats thanks to JFK and the 109. But there were also Higgins boats and another busy I can't think of right now. England also used torpedo boats as well as Germany. The English and German boats were mainly used in the North sea while ours were mainly in the Pacific. They were also in the Mediterranean.
At the beginning of the war our boats were relatively lightly and with only 4 .50 caliber guns and 4 torpedoes. Late war they were pretty beefy. Equipped with rockets, machine guns coming out of their ears, even a 40mm AA gun on the rear. I don't know exactly how armed the English and German boats were. The German schnellboots, had 2 tubes with door covers over the ends of them, probably to prevent the rough seas getting in the tubes.
Torpedo boats are a very interesting subject, especially because the Elco boats were so well known. I highly recommend reading into the subject more