From £500

Positives: high spec, well built and great value.

Negatives: an Ultrabook in name, not in spirit.

Intel has had a pretty good run. By designing and manufacturing the chips in nearly all of the world's PCs, Intel saw explosive growth arguably driven by everyone else's innovations – the desktop publishing revolution of the 1980s, computer games in the 1990s, and then the internet boosted sales of Intel silicon.

In 2006 Apple, the only mainstream computer company that didn't use Intel technology, switched its Macs from IBM to Intel chips. It's ironic then that Apple dented Intel's dominance four years later with the launch of the iPad, which used more power-efficient chips from Intel rival ARM.

Within two years, tablets were selling more units than all the computers from any PC manufacturer. Intel's answer is the Ultrabook, a blueprint for a small, thin laptop that combines the portability of a tablet with the usefulness of a PC.

The first generation of Ultrabooks from Dell, HP and Lenovo were fine machines, but retailing at more than £1000 they were double the price of most tablets and close to the price of Apple's class-leading MacBook Air.

Now second-generation Ultrabooks have affordable price-tags. I tested the Aspire Ultra M3 from Acer. Available from £500, the M3 is handsome, just 20mm thick and sports a sleek metal top and a high-quality plastic base. With a quoted battery life of eight hours, the machine exceeds the five hours laid down in the Intel blueprint. It returned closer to six hours for me – still plenty for a typical day of mobile use.

Unfortunately, the machine follows the letter of the Ultrabook spec rather than the spirit. At 2.3kg the machine is nearly 60% heavier than most Ultrabooks and its 15.6in display makes it much larger than most of the competition.

Surprisingly, it's wide enough to have a full-size keyboard and a separate numeric keypad, something usually reserved for 17in behemoths.

The machine feels surprisingly good when used on a desk. The keyboard is comfortable, the trackpad large and accurate and the screen crisp. The machine starts up almost instantly and apps open in a flash thanks to the 4GB of RAM on my test model.

On the move the Acer frustrates. The heavily-offset keyboard necessitated by the number pad is awkward to use on a lap, and the similarly left-leaning trackpad feels a real stretch for right-handed users. The chiclet keyboard, though well spaced and beautifully weighted, is hobbled by cost-cutting which sees the shift and enter keys share their "island" with other buttons.

If you need a home or office computer that you'll move occasionally the Aspire Ultra M3 is ideal, but if you need something portable I'd recommend something smaller and lighter.