Apple iMac (21.5-inch with Retina 4K display)

My four-year-old 21.5-inch iMac has been my faithful productivity work horse. Despite refreshes in design and chip upgrades to Apple's all-in-one (AIO) computer over that time, I have never felt an urge to upgrade. Until now.

The new 21.5-inch iMac comes with the option of a Retina 4K (4,096 x 2,304 pixels) display - perfect for owners of the new iPhone 6s or 6s Plus, as they can edit the 4K videos shot with their phones in their full glory.

The new display, which offers a 25 per cent larger colour gamut, makes my iMac's full HD display look like an old VGA monitor.

The extra colours will please photographers and graphic designers. But even casual users will be able to appreciate the vivid colours, better contrast and sharper image quality, which make icons and text look crisp and sharp. The display also looks good when viewed from an angle, as there is little colour shift. It is not as reflective as many glossy displays, even though you can still see your own reflection.

The new iMac retains the same beautiful physical design of its predecessor, with a curved back that tapers to a 5mm thick edge.

But it also means that all its ports are at the back. Having to reach behind to insert an SD card or USB cable is a major inconvenience.

The review unit, which has a base configuration, clocked scores of 3,767 and 12,970 in the 64-bit single-core and multi-core Geekbench 3 benchmark tests. On paper, the performance should be only slightly behind the 27-inch iMac with Retina 5K display reviewed last year.

One would expect at least a 7,200RPM hard drive for the price, but the base unit is configured with a 5,400RPM 1TB hard drive. This drive seems to put a drag on performance, and resulted in long waits to open even basic applications like iTunes and iMovie.

But when the applications are up and running, performance is pretty smooth. I have no problems playing and editing 4K videos.

NEW KEYBOARD AND MOUSE

The new 4K iMac, along with other refreshed iMacs, comes with the new Apple Magic Keyboard and Apple Magic Mouse 2. The new Apple Magic Trackpad 2 ($189) was also used for this review.

All these peripherals no longer use AA batteries, but are rechargeable using the Lightning cable. The Apple Magic Mouse 2 resembles its predecessor, except with the Lightning port underneath. This means it cannot be used during charging.

The Magic Keyboard and Magic Trackpad 2 are slimmer, flatter and have a Lightning port at their rear. You can use them while charging.

The Magic Keyboard takes up less surface area and its top row has bigger keys. It uses the same scissors-type switches found in the new MacBook. I found the keys responsive, but they feel shallow and lack the tactile response of their predecessor.

The Magic Trackpad 2 has a bigger surface area and is white on top instead of silver. Also, it is now a Force Touch trackpad, which means it can detect different amounts of pressure when you click, press or drag your fingers across it. Even if you are not used to Force Touch, this is still a very smooth trackpad to use.

Trevor Tan

• Verdict: If you want to edit 4K video on a budget, then Apple 21.5-inch iMac with Retina 4K display is a must-buy.