The Force looks a heck of a lot like the Flex. In fact, from a distance, you'd be hard-pressed to tell the two apart -- at least without the displays lit up. The most obvious difference is that the Force has an OLED screen, not just a series of LED dots that glow to indicate your progress toward a step goal. It's hardly high-res, but it doesn't need to be. It's large and pixel-dense enough to display simple icons and numbers; plus it's easily readable in direct sunlight.
Otherwise, the differences are quite subtle. The dark screen covering the display no longer wraps around the sides; instead there's a silver-gray plastic strip that works its way from one end of the display to the other. On the left edge of this band is a button that cycles through the display items and underneath is the proprietary three-contact charging port. Up close, you'll also notice that the Force is quite a bit wider than the Flex -- roughly 25 percent, to be precise. At three-quarters of an inch across, it's still small compared to even a standard wristwatch, but having worn the Flex for so long, I immediately noticed (and was slightly bothered by) the difference.
The screen is hardly high-res, but it doesn't need to be.
The band itself is the same lovely matte plastic, available in black and slate blue, with the same slightly frustrating clasp. It takes some effort to close the first few times you don the Force. Unlike the Flex, you can't remove the actual tracker and stick it in a different-colored band; it's built in. While you lose some of the fashionable flexibility, it's every bit as water-resistant -- as weeks of showering and dish washing have proven. And, despite the added bulk, it never got in the way while typing or got snagged in a sweater.
Under the hood, you'll find a whole host of electronics, including an accelerometer for counting steps and an altimeter for tracking flights of stairs. Plus there's NFC, a vibrating motor for silent alarms, Bluetooth 4.0 for wireless syncing and a lithium-ion battery rated to last up to 10 days. In our time with the device, we'd say that estimate is slightly conservative: We were able to go 11 days between charges... twice. And when it does come time to plug the Force in, you can charge it to 100 percent in less than two hours via your computer's USB port.
This time around, thankfully, Fitbit ditched the wonky accelerometer-based control scheme. Pressing the button wakes up the wearable and displays the time. Press it again and it starts to cycle through your steps, total distance walked, calories burned, flights of stairs climbed, "very active minutes" and your alarms.
One wrinkle this adds, however, is that while it's easier to start and stop sleep-tracking mode, it's much less convenient. Rather than a series of taps, you use the companion app to tell the Force when you go to sleep and when you wake up. Not only is it difficult to remember to do this every night and morning, but it also means you can only track your sleep with a very select set of Android devices or an iPhone newer than the 4s.
Update: There is a much less cumbersome way to start tracking your sleep: simply press and hold the button on the left hand side to put the Force in stop watch mode. When you wake up, simply long press the button again.
Since the Flex came out, Fitbit has updated its apps with a fresh (if somewhat subtle) coat of paint and also added a few new features. Both the iOS and Android versions rock a much flatter aesthetic, with colorful icons indicating the different metrics it tracks. It makes the UI easier to navigate at a quick glance. Unfortunately, while the clean design is easier to navigate, many of the options are still buried behind several layers of menus. For example, telling the app to start tracking your sleep is at least a three-tap affair: From the dash you have to select the sleep-tracking option; then you have to tell it that you want to log your sleep; then you have to tell it to start tracking now. And, while the sleep tracking seems marginally improved over the Flex, the feature was inconvenient enough that I stopped doing it after the first week.
The calorie-counting feature is equally cumbersome. While anecdotal evidence suggests the database of food items has improved slightly (I still managed to stump it with a number of items), adding meals is time consuming. You can't add foods in batches and there's no barcode scanner for quickly pulling up nutritional info for packaged or prepared foods. And that nutritional data is limited to calories only, so you'll have no idea what percentage of your diet is protein, fat or carbohydrates.
Exercise tracking isn't any more efficient, but it doesn't demand the same level of attention or input, so it feels less burdensome. Even the most diehard gym rat tends to take a day or two off from exercise, and you're much more likely to repeat the same exercise multiple times a week than you are to eat the same dinner. These features continue to be the weak spot in the Fitbit ecosystem. Tracking this additional data is nice, but inconvenient enough that you'll probably just ignore those fields. And, honestly, if you discount them and focus on simply tracking your steps, your experience with the Force will be that much more pleasant.
One feature we unfortunately have been unable to test out is notifications via iOS 7. In the near future, a software update will make it possible to view caller ID info on your Force when connected to an iPhone running the latest version of Apple's mobile operating system. However, Fitbit has yet to give a definitive launch date. And, with only call notifications being supported, the feature is of questionable utility. After all, who actually uses their phones to make calls anymore?
It may be hard to believe, but when the Flex came out just six months ago, it was entering a much less-saturated market. And, since the Flex is still for sale, along with the One and Zip, Fitbit is competing against itself. Among the company's own options, the Force is the clear winner. It combines all the features of the One with the convenient, wrist-worn form factor of the Flex. But there is still plenty of stiff competition from the outside. Withings' Pulse, for instance, boasts most of the same features, sans always-on Bluetooth, in a belt-clip design for $100. Nike's new FuelBand SE costs $20 more than the Flex, and favors "Fuel points" over an actual step count, but does have an extremely robust social side that Fitbit can't quite match. Then there's the Up. Jawbone's wearable has its fans thanks to its Yves Béhar design pedigree, but with so many fewer features than the Force at the same price point, it's a tough sell.
The Force is, in many ways, an ideal mashup of its previous Flex and One fitness trackers. It's a souped-up, feature-rich, wrist-mounted pedometer. And when you look at it from that angle, it's an unmitigated success. It accurately counts your steps and does so while largely staying out of the way. Unlike the Up or a full-fledged smartwatch, the Force never gets caught on clothes or becomes an annoyance while typing. It's damn-near indestructible, battery life is stunning and the display puts an impressive amount of data at your fingertips. But, it still suffers from many of the same shortcomings as its predecessor. And, with increased competition from Nike's new FuelBand SE and the Withings Pulse, Fitbit can't afford to ignore its weaknesses.
If you can learn to live without the things that the Force doesn't excel at and treat it purely as an extremely fancy step counter, then you could potentially learn to love it. There is a major caveat, however. At $100, the Flex was an easy sell and clearly offered the best bang for your buck. At $130, you can't make the same argument for the Force. The screen is certainly a nice to have feature, but without price on its side, Fitbit's victory is less clear-cut.
Update: On February 20, 2014, Fitbit announced a voluntary recall of all Fitbit Force units due to reported cases of contact dermatitis caused by the device. As Fitbit has halted sales and is offering a full refund for units already sold, we can no longer recommend this product. We have withdrawn our Engadget Score until the problems are resolved.