The new 21.5-inch Apple iMacs have been on sale since the November 2012 refresh, but we had to wait around a month before the larger, 27-inch models hit the shelves.

They're certainly worth waiting for. Packed with new technology and boasting an exciting new form factor, the late 2012 27-inch Apple iMacs are incredibly stylish and have a performance to match.

The 27-inch iMac was first introduced in the late 2009 refresh. Numerous Windows PCs boasting a similar all-in-one form factor with a large-format display have sprung up since, with some proving more successful than others.

One of the better recent releases is Dell's XPS One 27 Touch, a powerful machine that costs less than even the cheapest 27-inch iMac. The HP Z1 WM429EA has an excellent build quality and great IPS screen, but is expensive for its performance.

Sony's Vaio L series all-in-one PC is very stylish and boasts a Core i7 processor, but at 24 inches, its screen isn't as big as the 27-inch iMac's.

As is the norm for recent iMac refreshes, the 2012 range offers two 21.5-inch releases and two 27-inch models. Off the shelf, they all boast Core i5 processors, 8GB of RAM and 1TB hard drives.

The model on test here takes advantage of some of Apple's customisation options offered through the Apple Online Store. Based on the more expensive of the two 27-inch iMacs, its processor has been upgraded from a 3.2GHz quad core Intel Core i5 to a 3.4GHz quad core Intel Core i7.

The Nvidia GeForce GTX 675MX 1GB GDDR5 graphics processor has also been boosted to a GTX 680MX with 2GB, and we swapped its 1TB hard drive for a new Apple 1TB Fusion Drive.

Memory remains unchanged at 8GB of 1600MHz DDR3 SDRAM, but unlike the 21.5-inch models, the 27-inch iMacs can be user-upgraded. They can also take a maximum of 32GB, compared to the 21.5-inch iMacs' 16GB.

This upgraded version of the 2012 27-inch iMac is priced at £2,179/AU$2,889/US$2,599.

Like all new Macs, the 2012 iMacs come supplied with Mac OS X 10.8 Mountain Lion and the latest version of Apple's iLife software suite.

As standard, they're supplied with a Magic Mouse and a wireless Bluetooth keyboard that has no numeric keypad. Order on the Apple Online Store and you can replace the keyboard with a full-sized USB model and/or replace the Magic Mouse with a Magic Trackpad, free of charge.