The design of the Fitbit Flex is the very definition of simplicity. And we don't mean that in a bad way. Some might say it's bland, but we like to think of it as tasteful. Understated. There's a bit of retro-futurism to the aesthetics here. In fact, it looks like something
Dr. David Bowman Frank Poole might have worn while jogging around the Discovery One. (Editors note: as pointed out in the comments, it is in fact Frank Pool, not Dr. Bowman jogging around the spaceship in 2001: A Space Odyssey.) The entire band is made of matte plastic, in this case a gray-blue the company calls "Slate." The only interruptions along the sleek and simple body are the brushed-metal squircle you press to close it around your wrist and the thin, dark plastic window that exposes the lights on the tracker piece. It's quite a bit bulkier than the Up and there's a slight taper to the body, with it getting a bit thicker where the window is. But, the more watch-like design actually makes it more comfortable to wear than the Up, which constantly gets caught on things and scrapes against your laptop. If the Flex didn't need to be charged every few days, you could almost forget you were wearing it.
The design of the Fitbit Flex is the very definition of simplicity. And we don't mean that in a bad way.
The band itself is just that: a band. The tracker is actually a removable piece that slips inside the rubber strap. It's small, black and completely inconspicuous. One side has a sharp slope and a lightly etched Fitbit logo and the opposite end has three metal contacts used with the charging dongle. The only other external features are the five white lights along one edge, which shine through the window on top of the band. Unless you want to constantly have the app fired up, these will be your primary way of interacting with the Flex.
The accelerometer inside, meanwhile, doesn't just count your steps or measure how restless your sleep was; it also provides a way of controlling the device. Tap the module twice and the lights will tell you how close you are to your step goal; tap it five times to tell it when you're putting your head down to catch some shut-eye (and five times again when it's time to start your day).
It's a bit tricky to get the Fitbit to register five taps in a row to take it in and out of sleep mode -- especially first thing in the morning, when you're bleary-eyed and desperately want the silent alarm to stop vibrating. And, yes, there is an alarm on board, but unlike the one on the Up, it simply goes off at a predetermined time. Meaning, it doesn't actually wait until you're in a lighter stage of sleep. While the accelerometer is a bit fickle when it comes to controlling the Flex, we can't overstate the convenience of being able to glance at the band to track your progress towards a step goal. Each of the five lights represents 20 percent of your target number of steps (by default it's 10,000). When you reach that goal, the band vibrates and the LEDs do a little happy dance to congratulate you -- it's much more satisfying than plugging into a phone and waiting for it to sync.
The convenience of being able to track your progress towards a step goal on the band itself can't be overstated.
It's impressive enough that there's a battery able to get you an estimated five to seven days of use inside, along with the accelerometer, LEDs, motor and necessary processing power. But there's also a Bluetooth 4.0 radio and NFC hiding in this tiny wonder. Combine that with the included USB dongle or the updated mobile app and you can sync your activity, sleep and change your alarms without having to physically connect the Flex. It's one of our favorite features, especially on the few compatible Android handsets, which let you tap the phone on the wristband and automatically launch the Fitbit app and initiate a sync using NFC. Even if your phone isn't one of the currently compatible models (the Galaxy S III, S4 and Note II), the inclusion of NFC lets you quickly launch the app with a tap, though there will be no ability to sync.
As you'd expect, the Flex is also built to be quite indestructible. Fitbit bills it as water-resistant, not waterproof, so we wouldn't suggest you take it for a long dip in the ocean. That said, it survived plenty of showers and dishwashing sessions. While the tracker is rated to survive up to seven days of such abuse, we usually needed to give it a charge every five. Still, that's better than the FuelBand.
Like the Flex itself, Fitbit's mobile app is clean and simple. There are no extraneous colorful graphics or smiley-face avatars here -- just numbers, graphs and a few helpful icons on a gray background. Not much has changed since the update, delivered back in February. You navigate between sections from a drop-down in the upper-left-hand corner and can swipe through a few different panels on the various summary cards on the home screen. The dashboard gives you quick access to your alarms and food plan, while showing your progress towards various goals such as calories burned. Unfortunately there are a few features that would seem like a natural fit for simple-to-tap shortcuts, such as the ability to add to your food log, that are sadly missing.