I just started playing with my Thermapen. When this thing says "instant" read, they are not kidding. I have never seen a thermometer react so quickly.
It was also cool that it was calibrated before going into the package and comes with a certificate of calibration, including the name of the calibrator, date, temp and humidity, and reference instruments.
Other cool little details I didn't know: there are DIP switches in the body that let you change between F and C, change the resolution from 0.1F to 1F, disable the auto-off function if you want it on all the time, and adjust the trim if it ever drifts out of calibration.
This is closer to a laboratory instrument than a kitchen thermometer. It's no wonder they're so expensive.
-Joe