The accuracy of the Footpod has been surprisingly good when comparing it to the mileage on the treadmill, it is spot on for the shorter distances and has had a minimal variance of - 0.12 over 12 miles, as a comparison my Nike+ was -0.50 which is pretty typical in my experience of Nike+ on a treadmill over distance. As with any accelerometer the key to it is to keep a steady pace, given that I still have a red flag from my PT on speed and hill work plodding along on a treadmill is just perfect. As with all exercise sessions using a the Forerunner you get a comprehensive breakdown on data in a graphical format, with the only exception being the exclusion of altitude.
The Footpod is completely compatible with the features and settings within the Forerunner watch itself; mile splits, average pace and average speed are all calculated and the alert function works seamlessly with the little chimes ringing out every mile. Garmin also offer a handlebar mount which may be more convenient if mounted on the bars at the front of a treadmill, that way you can glance down without having to bring the watch into your line of sight, that maybe something for the future.
Although early days I am very impressed, the Forerunner's popularity has been based largely on the GPS function which allows you to accurately calculate pace and distance; two important factors to the runner, now the needs of the indoor runner have been addressed which adds to the all round capability of theForerunner as a training tool.