I first tried these peppers at a local sushi place in downtown Kirkland called Sushi Joa. They were roasted or grilled and slathered with a sauce that was sweet and savory. Since then I have gone back three times to eat the same dish. This is a trendy gourmet pepper that is popular with chefs.
Shishito peppers have thin walls and it is reputed that 1 out of 10 is spicy. The rest of the 9 tend to be very mild. They are usually harvested when they are green and grilled or roasted but they also make a great pepper tempura. I found several recipes here.
The pepper plant itself is small (about 12 inches or so tall, although I have heard of them growing taller) and yields a medium-heavy crop of peppers, I planted 3 plants because I wanted tons of them. I harvested once a week and usually ended up with 2-3 dozen peppers per week. These plants are remarkably drought tolerant (I only watered them once a week) and disease free. They were super easy to grow and I recommend growing them in a large pot or in a raised bed.
Pepper are 2-4 inches long, Don't mind the stunted red one, it was probably not fully pollinated.
* Note: With all peppers, plant outside when the weather is warm. 55 F in the evenings.