Manufacturers the world over are trying to solve the problem of how to build the perfect convertible Ultrabook, and Lenovo believes it has the answer with the ThinkPad Helix. I spent some time with a pre-production model at CES 2013, and in the main I’m impressed.

While I’ll come to its foibles later, let’s first take a look at the number of problems it solves.

One – people want the option of a high-speed laptop when they need it, but they don’t want to hold something horribly heavy when in tablet mode. Check. The 835g screen lifts from the hinges if you press down on the catch to the left.

Two – they want power, but they also want enough battery life. No problem. You get six hours of life from the tablet and a further four hours from the base. Bearing in mind this is a full Ultrabook, so a Core processor will be inside, that’s an excellent compromise

Three – you want a machine you can do proper work on. Again, check. The ThinkPad Helix includes a full keyboard with 1.6mm of travel, and as you’d expect from a ThinkPad it’s a pleasure to type on.

The 11.6in screen is a respectable choice for using at length, and it’s helped by being so bright – according to the specs, it’s a 400-nit display. We appreciate the 1,920 x 1,080 resolution too.

It’s also clear that Lenovo has put a lot of thought into the way people will use the Helix. It’s weighted the tablet screen so that it’s less inclined to tip when in laptop mode – a big problem with some other convertible tablets – and it tilts back by up to 135 degrees, which is enough.

It’s harder to be convinced by Lenovo’s claims that there’s a genuine advantage from one of the Helix’s key features: that you can “rip and twist” the screen so the screen faces in the opposite direction to the keyboard.

To quote Lenovo’s press release, “this mode, called Stand mode, transforms Helix into a mini-movie theatre or business presentation central”. If you do end up buying the Helix, do let me know how many times you actually do either of those things.

The release goes on to say that, from the Stand mode, “users can also fold the screen down to use it as a tablet while keeping the base connected for added ports and connectivity”.

Again, I’m doubtful as to how often most people will want to do this, but I’m happy to be corrected in the comments below. For the record, the tablet includes a USB 2 and mini-DisplayPort. The base adds two USB 3 ports and duplicates the mini-DisplayPort.

The questions then come as to whether the design decisions Lenovo has made in order to give this level of flexibility make sense. Here are two:

Above left you’ll see the shape of the tablet, which looks like it’s been sliced off at the bottom to leave a suspiciously flat edge. And above right is a close-up of the right-hand hinge mechanism: you have to slide the tablet precisely over this, and its mirror image on the left, to put it back into place.

Hopefully the photo above, which shows the bottom of the tablet itself, gives you some idea of how this works in practice. It also shows the slot for the SIM card (two thirds from the left), the mini-DisplayPort and a power port – you can charge the tablet directly.

However, note that the Helix doesn’t include an SD card slot. Personally I’d find that a big drawback because I frequently use SD cards to transfer photos from my camera.

So the ThinkPad Helix probably isn’t yet the perfect convertible Ultrabook, but in reality that’s never going to be possible. Sacrifices have to be made somewhere, whether that’s to battery life, the choice of operating system or the quality of the keyboard.

Despite my criticisms, I must admit that I’d love to try the Helix for a couple of weeks and put it through some real-world tests. I suspect I can live with the foibles in return for getting an Ultrabook with ten hours of battery life and such a good keyboard.

As soon as Lenovo has full production units, rest assured PC Pro will be clamouring on the door to grab the first samples. And I’ll probably “borrow” it from the reviews editor when he isn’t looking.

Key specs

• Intel Core i7 processor
• Up to Windows 8 Pro
• 11.6in 1,920 x 1,080 IPS display with pen inut
• 865g tablet, 1.7kg with keyboard
• Up to ten hours battery life with keyboard
• Up to 256GB SSD storage
• Up to 4GB DDR3 memory