I bought this Best Buy and finally got all of my files, music, and movies downloaded and settings as I want them, and have had a chance to play around with it. I have two other Macs (a three year old Mac Air I use for travel and a Macbook Pro I bought at BB in early May that I love). I wanted something with a larger screen for the house that I could move relatively easily, but didn't want a traditional desktop, with all the cables and room that requires. This one fits the bill nicely.
Mine is the 21" with the Retina display. The screen is absolutely gorgeous. The PC is very quiet, and there is no fan or hard drive noise that I can discern. I got this one after ruminating for several days whether to get the 21" or 27" (both were on sale at Best Buy), and this one fits my needs a bit better in terms of size and was a bit cheaper.
If you spend a lot of time online and doing basic tasks, or you like to watch movies, this thing is wonderful. Wireless connection speed is excellent and it does have a traditional ethernet port, unlike the new Mac laptops, if you want a wired connection. It also has a standard SD card slot in the back and accepts standard-form SDXC cards, unlike my Macbook Pro, which required a proprietary card.
Keyboard is very small, light and flimsy-looking but works well and, like the included Magic Mouse, is rechargeable via the included lightning to USB connector. A standard iPhone lightning cable will perform the same function.
Only negative is the included 5400 rpm 1 TB hard drive. I knew this included that when I bought it, but couldn't justify the huge premium Apple charges to move up to a Fusion or especially Solid State drive, and those are difficult to find in retail stores, so you'll likely need to configure and order it on the Apple website, and then you'll pay full markup without a sale like the kind Best Buy routinely offers. Nonetheless, the base drive is painfully slow at times, and this iMac's boot up and general feel are noticeably much slower than either my MacBook Pro or Air, despite similar (or more, vs. the Air) memory and a much-superior processor.
Memory is adequate at 8 GB and, in the 21" version, is not upgradable. The 27" version does still have user-accessible slots and you can add memory. The hard drive is not easily upgradable in either and not something I'd recommend anything other than an advanced apple user attempt, and would probably void your warranty. In mine though, I installed a memory management program and utilization seldom goes over 60%, so 8 GB should be fine for now.
The form is beautiful and the display quality is flawless. Once again, excellent Apple execution EXCEPT I'm really disappointed that they made the decision to put such an archaic hard disk in an otherwise premium computer, and it's not designed to be able to upgrade. Online tasks and general usage are fine, however, once everything loads up.
Overall, still a really nice machine and I would recommend, with the caveat that people are aware of the obsolete, slow hard drive that can really impact performance feel.