There's an analogy to be made between the Lenovo Yoga Book and its namesake practice. Done well, yoga provides functional fitness for any task at hand. When poorly executed, it's frustrating and injurious. Yoga Book lands somewhere in between.

This novel 2-in-1 tablet/notebook is one of many hybrid devices that attempt to streamline the best features of pre-existing technologies and adapt them to fit our lifestyles. Our test model is a mobile version powered by Android, but there are also desktop-powered variants that run Windows 10.

At first glance it looks like a small laptop. But the display is a touchscreen, so you can navigate with taps and swipes. Instead of a clamshell hinge, the display can bend completely forward or backward, so you can use it as a tablet with the keyboard slate concealed underneath.

I say keyboard slate because it's just that – a smooth black slate where physical keyboard buttons would normally be. Yoga Book doesn't have physical keys, only a backlit QWERTY keyboard (dubbed the "Halo keyboard") that appears on the platen when the device is running in keyboard mode. Switch to drawing mode, and the keyboard disappears, letting you use the included stylus to write and draw instead.

Where Yoga Book delivers: Concept, build, price

I welcome the concept of a 2-in-1 tablet/notebook, and even Lenovo's interpretation of it. A book-sized device that you can use as casually as scrap paper or as intently as a computer? Sign me up. Delivered elegantly, it could become the ultimate note taker. That may not be a glamorous title, but it's one of near-universal utility.

The Yoga Book stays promising beyond the first glance. While not exactly drool-worthy, the matte black metal case (also available in gold or gunmetal gray) is attractive enough. It occupies a sizing sweet spot: Not so small it's impossible to type on, but not large enough to be inconvenient to carry. The Book is somewhat heavy for its size, but that heft provides a solid foundation on which to write. It's highly smudge and scratch resistant as well.

Since we're accustomed to seeing mobile devices with little or no exposed hardware, I can't decide if the Book's "Watchband Hinge," seen in previous Yoga devices, is eye-catching or an eyesore. It's made up of bundled metal rods with rolling cylindrical gears. These mechanical parts would look more at home on an airship or the Game of Thrones set than on this year's mobile technology, but it works great, so I'm sold. The hinge stays in place at every angle, and it's easily adjustable when you need it to be.

The Yoga Book is US$500 for the Android version or $550 for the Windows version, so Lenovo also gets points for affordability. With all of its decently-packaged flexibility, this seems like a high-value device for the price. Theoretically, it supplants the need for a separate tablet, laptop and pen-and-paper for about the cost of last year's iPhone.

Where it fails: Hardware overkill, software overwhelm

But those build details aside, the Yoga Book's outstanding feature is the number of different ways you can interact with it. Type on the Halo keyboard or draw on it with a stylus. Put a ballpoint tip on on the stylus and you can draw on paper while it is digitized onscreen. Tap and swipe the display like a tablet, or use the trackpad below the keyboard. Most of these input devices work passably well on their own, but the way they come together is chaotic.

For example, the digital typing experience surpassed my expectations, even if it's still a little questionable. In Lenovo's defense, the idea is not inherently preposterous. After all, we have no problem texting away on our smartphones, and the Yoga Book is primarily mobile technology dressed up like a laptop. I actually found the unfamiliar size of the keyboard more disruptive than the lack of keys.

True blue touch typists might struggle with the keyboard, but I'm convinced that those types are increasingly rare, as we all get used to typing on different types of devices. There's also a predictive text feature that works well and has proven useful at correcting most mistakes and learning your typing style.

So my primary qualm with the keyboard isn't its lack of keys, but its jumbled feeling. I keep accidentally resting my hands on the trackpad as I type, because it's crammed in so close. This annoyance is exacerbated by the fact that the trackpad seems to be the biggest weakness: Gestures don't seem to work well, and it's touchy at all the wrong times. Another, stranger problem is that while typing, I've inadvertently turned the keyboard to French several times. Quelle horreur! I'm not sure exactly how this is happening (I presume some kind of keyboard shortcut) but a cursory Google search suggests I'm not alone.

I have similar observations about using the Real Pen stylus. It's sufficiently pressure-sensitive (2,048 levels) for most writing and doodling applications. It works well in isolation, but not always in a way that facilitates workflow.

Like any plastic-nibbed stylus, it can be used to draw directly on the keyboard area/drawing slate. My only disappointment here is that the stylus doesn't work on the touchscreen, so when you're using the Yoga Book as a tablet, it's fingertip-only.

The other way to use the stylus is to swap out the plastic nib for one of the included ballpoint ones and write on actual paper. It's designed to work with the bundled Book Pad, a pad of paper that magnetizes in place on top of the slate. When you write on the paper, your notes are magically digitized on screen. That perk is rare even among drawing tablets.

But with this multi-faceted nature comes complications. Changing the nibs is a clumsy process – you have to use the pen cap to work them out of the pen. There's no convenient storage for the stylus or its nibs, and the device is not compatible with any other type of pen. Replacing a Real Pen costs $40; it's $15 for a set of ink refills. On the plus side, I have noticed that other sheets of paper, placed on top of the keyboard slate, works just as well as the bundled Book Pad, though BYO-paper does not seem to fall within manufacturer's recommendations.

Beyond its finicky parts, software limitations are really holding the stylus back. When you're using the stylus (just hit the built-in button to switch between keyboard and drawing mode), Lenovo's Note Saver apps automatically fires up. Note Saver can save as a PDF and share notes with third-party apps, but since it doesn't back up to the cloud, you're probably better off starting out with an option like Evernote in the first place. So you'll constantly be running away from the Note Saver, or trying to back it up.

Third-party app support seems rather glitchy as well. The first few attempts at using the stylus in Evernote failed; things seem to get temperamental when there are too many apps open at once. Lenovo put some twists on Android Marshmallow to give it more laptop-like functionality, but those capabilities don't extend far below the surface.

For example, there's a good multi-window feature so you can see more than one app at a time, which is essential for activities like watching a video in one app and taking notes in another. However, many key apps (like Google Docs) don't support multi-window mode. You also have no control over the size of the windows – they are automatically sized into columns that take up about a third of the screen. And with multiple windows open, performance, which is less than impressive to start with, slows down noticeably.

All in all, the dressed-up Android operating system shows promise, but it's less than perfect. Even without trying the Windows version, I'm tempted to say it would be worth the upgrade to get away from the mobile operating system, though of course more robust software may introduce problems of its own.

Beyond the Yoga Book's many input devices and souped-up mobile OS, most of its other features are unremarkable. It does have a strong battery; I squeezed at least nine hours out of a full charge. It's not a photography-driven device, but the front and back cameras get the job done. The display is a little disappointing; low resolution and high brightness makes for a cheap look and color inaccuracy. The sound and microphone are a bit tinny and muffled, but just fine for personal video watching on a budget device.

Pros & cons

All in all, I'm impressed with the innovation and boldness of the Lenovo Yoga Book. Still, I can't help but wonder if all those input options are overcomplicating things. Either way, they demand an operating system that can marry their functions seamlessly without breaking a sweat.

That being said, it's not a stretch of the imagination to picture college students or certain professionals using one of these and liking it very much for specific applications – as long as they are prepared to work through some rough spots.

If the Yoga Book had a more polished delivery, I'd be thoroughly impressed. For now, the less-than-perfect aspects stunt its hard-won flexibility and cripple that excitement. Maybe future generations will head in the right direction, but until then, I'd stick with solid, if less novel, 2-in-1 options.

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