There are actually 3 new trackers, all designed to be worn on the wrist. The Fitbit Charge and Fitbit Charge HR are similar so let's talk about those first.
The $129.95 Charge tracks steps, distance, calories burned, floors climbed and active minutes. It also tracks your sleep patterns and has an alarm feature that vibrates the device to wake you up. Last up are a caller ID feature and wireless syncing to a large number of cell phone models. (There's a complete list on the Fitbit site.) As far as I can tell the Charge is a pretty direct replacement for the old Fitbit Force; only the caller ID feature is new.
The $149.95 Charge HR does everything the Charge does plus adds heart rate monitoring (via a sensor on tracker itself, no additional wires needed), plus the ability to identify the start and end of specific workout periods.
Fitbit's third new device is the $249.95 Surge, which they're calling a "Fitness Super Watch." It has the tracking and heartrate monitoring of the Charge HR, plus adds GPS tracking, call and text notifications from your phone, and music controls. It also features a much larger display than the other devices.
Only the basic Charge is currently available but you can sign up to be notified when the Charge HR and Surge are ready. Word is that won't be until early 2015.
All three devices now come in Small, Large and Extra Large sizes and Fitbit urges users to wear them loosely enough that you can slip a finger inside the band. Remember that they had to recall the Fitbit Force due to people having allergic reactions to nickle used in its construction. Now there's a whole page devoted to 'Wear and Care' that seems intended to minimize any similar complaints. We get tips like "Prolonged rubbing and pressure may irritate the skin, so give your wrist a break by removing the band for an hour after extended wear."
If you purchased a Fitbit Force you may have received an email offering 15% off the Charge, or the older Flex or One models. (You need to have bought a Force from Fitbit or its authorized dealers and registered it on Fitbit.com, and you must reside in the US or US Territories to qualify; if you didn't get the offer it might be worth contacting Fitbit to see why not.) I'm going to tuck that email away to see if it also applies to the Charge HR and Surge once they become available; the code is valid until June 30, 2015.