The most exciting thing about the 2012 27-inch iMacs is the new technologies Apple has packed in. The casing is a significant departure from the previous generation, adopting a beautifully slim look.

At its edges, it's just 5mm (0.2 inches) thick, which makes it around 80% thinner than the previous design. The iMac as a whole is around 40% smaller by volume.

Naturally, there's a bulge in the centre of the rear of the display - you could hardly hide the iMac's components in a casing that's 5mm thick throughout. But it's so cleverly designed you need to see it in profile before you realise the bulge is even there. From any other angle, the new iMac looks as thin as its edges. It's this attention to design detail that really sets Apple computers apart from the crowd.

The new iMac's screen has also been revamped. It's still an LED-backlit display with IPS technology and a pixel resolution of 2560 x 1440, but several key enhancements have really boosted its performance.

The display is now fully laminated, which means the LCD sits against the covering, eliminating a 2mm gap and preventing reflections on the inside of the glass. This has never before been attempted on a screen this size.

A new plasma deposition process, more commonly used for smaller surfaces such as camera lenses and fighter pilots' visors, means an anti-reflective coating can be applied very precisely, in an extremely thin layer to preserve the integrity of the colours. The new display cuts reflections by around 75%.

Apple's new Fusion Drive, which is available as a custom option on the Apple Online Store, augments the traditional hard drive with 128GB of solid state storage.

The operating system and your most often accessed files are stored on the speedy solid state section, while everything else is kept on the main hard drive. This hybrid solution gives near-SSD speeds without compromising capacity. The model under review here has a 1TB Fusion Drive, but a 3TB version is also available.

If you prefer to stick with the off-the-shelf drives, you get a 1TB HDD that runs at 7,200rpm. This is welcome news considering the 21.5-inch iMacs were downgraded to 5,400rpm drives for this generation.

All the new iMacs use Ivy Bridge processors, the third generation of Intel's Core-i series. These boast Intel HD Graphics 4000 integrated graphics.

Little has changed around the back. The new iMac still has two Thunderbolt ports, Gigabit Ethernet and an SDXC card reader. Its four USB ports are now high-speed USB 3.0.

The FireWire 800 port has gone, but you can buy adaptors and use your FireWire peripherals in the Thunderbolt ports.

With the 2012 refresh, the iMac joins the Mac mini and the MacBook Pro with Retina Display in losing its optical drive. If you still want to use CDs and DVDs with your iMac, you have to buy an external solution such as Apple's USB SuperDrive.