The jalapeño pepper has a Scoville heat scale of 5000-8000. It is not bitter and, unlike hotter peppers, has a flavor. It reminds me of a regular green pepper, only hotter.
The heat is not constant, the effect is very short-lived – it lasts for a few minutes. It can be eaten fresh or pickled.
It is often added to pizza, burgers, and eaten with meat. My favorite way is to eat sliced fresh or pickled jalapeño with meat.