The Fitbit Force is essentially an upgraded Flex, says the Verge, but with an altimiter (to track stairs, presumably), an added activation button and an alphanumberic display where the Flex just has a series of dots. Addition of a button means you won’t have to tap the device like a maniac to change modes; addition of a alpha display means it can also work as a watch — a big improvement.
Pricing, the Verge says, is $129, up $30 from the Flex. Availability was not stated. It’s worth noting that although Flexes themselves appear to be readily available from FitBit, Flex accessories in the online store show a 6 to 8 week backorder.