Apple has always been known for superb picture quality especially with its Retina models. With Apple line of notebooks though, it's sometimes hard to really applicate the Retina's resolution unless you plug your Apple notebook into an external 4K display.
Unfortunately, finding an affordable color accurate 4K monitor is difficult. Apple address this with the iMac with 5K Retina all-in-one computer. Given the amazing display used, the iMac with 5K Retina is surprisingly affordable, especially given the cost of similar high end color accurate 4K displays out there.
As a Mac user, once you get used to the Retina display, it's hard going back. Now with the Retina 5K iMac, the clarity of the display and the crispness of every single pixel is even more exhilarating. With this large screen size, you can get easily immersed into what you are viewing.
The display is awesome for professionals involved with video or photo editing. However, even for other jobs where you need to look at the screen all day, the 5K Retina display makes work more comfortable. Apple has taken great care in the design, making sure that glare and reflections are at a minimum for a glossy display.
The iMac with Retina 5K comes with a Bluetooth keyboard and mouse. Moreover, it has four USB 3.0 ports, two Thunderbolt 2 ports, one SDXC SD card slot, one Gigabit Ethernet port, and one headphone output jack. Unlike its smaller notebook cousin, this iMac has all the ports you will need built in.
Apple has kept a strong design philosophy of combining performance with aesthetics. The iMac with Retina 5K keeps to this philosophy and is designed to impress.