We have truly entered the era of the quantified self. Editorials are 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.

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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 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 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.

The Flex is entering an increasingly crowded marketplace. Wrist-worn fitness trackers are a hot commodity right now and making your mark in the field is becoming quite difficult. But Fitbit might just have struck the right balance between price, convenience and simplicity. Some of its competitors certainly hold advantages over it in particular categories. For example, the Jawbone app, despite all of its half-baked features, certainly outclasses Fitbit’s — especially in the calorie-tracking department. And Nike’s more robust display puts a lot more data at your fingertips. But the Flex manages to pack more features than the FuelBand, more convenience than the Up and undercuts both on price.

What Fitbit seems to have done is look at the rest of the fitness-tracking field, figure out what features have proven most successful and essential and then packed them in a surprisingly stylish and affordable package. At $100, the Flex isn’t an impulse purchase considering its relatively niche appeal, but for those looking to pick up this particular type of lifestyle product, it’s a solid choice. The social aspects of racking up Fuel points and Jawbone’s more robust mobile app certainly have their appeal, but we’d say the Flex offers the most well-rounded experience, not to mention the best bang for your buck.