As you'd expect, the new late 2013 iMac comes in four configurations, the two 21.5-inch models reviewed here, and two 27-inch versions. The 21.5-inch iMacs cost £1,149 (about US$1,850, AU$1,900) and £1,299 (US$2,100, AU$2,160) respectively, both somewhat more expensive than their 2012 counterpart.
Their processors have the same clock speeds as before, at 2.7GHz for the cheaper one and 2.9GHz for the more expensive, and they're still Intel quad core Core i5s, with an upgrade option for a 3.1GHz Core i7 chip for the more expensive 21.5-inch iMac only.
At times of high processing needs, the CPUs can Turbo Boost up to 3.2GHz and 3.6GHz respectively, though the quad core Core i5 chip doesn't have Hyper Threading, whereby each of its cores can run two threads. If this feature is important to you, go for the Core i7 upgrade option, which can run two threads on each of its four cores, giving eight virtual threads.
For graphics, the higher-specced 21.5-inch iMac has an Nvidia GeForce GT 750M with 1GB RAM, which is up from the Nvidia GeForce GT 650M used last year. The entry-level model, however, drops the discrete graphics chip altogether, and relies on the new Haswell processor's integrated Intel Iris Pro 5200 graphics.
While integrated graphics chipsets share memory with the CPU, Iris Pro also adds 128MB of DRAM for extra memory bandwidth. We're promised it will at least match the GeForce GT 640M used last year.
Both of the new 21.5-inch iMacs have 8GB of 1600MHz DDR3 memory, which is a generous allowance, but as mentioned before, it's not user upgradeable. If you think you need more, best use the online custom option and increase it to 16GB for an extra £160 (about US$260, AU$270).
Both models also have a 1TB hard drive out of the box. Unfortunately, they're 5,400rpm, unlike the 27-inch iMacs that have faster 7,200rpm hard drives. Storage can be upgraded to a Fusion Drive, which combines a 1TB hard drive with flash storage, or a solid state drive of 256GB or 512GB capacity.
Both 21.5-inch releases are now WiFi ac, giving up to three times as fast wireless connectivity when used with a compatible router, and both offer Bluetooth 4.0.
For peripherals, there's two Thunderbolt ports, four USB 3.0 ports, gigabit Ethernet and an SDXC card reader slot. Both come with the latest version of OS X installed (10.8: Mountain Lion at the time of writing, but they'll be upgraded to 10.9: Mavericks as soon as it's released).
Apple's respected lifestyle suite iLife is also bundled, including iPhoto, GarageBand and iMovie. All iMacs come with a wireless keyboard and a Magic Mouse, but if you order online, you can swap them for a USB keyboard with a numeric keypad and a Magic Trackpad respectively at no extra cost.