If anyone is on the fence about buying a Retina Imac they should go to the Apple Store and see for themselves if that is possible. All of these little nitpicking issues you read about on this forum were not a issue for me when I went to the Apple Store, and played around with the base model iMac Retina for a while.
Now that I've had mine for close to a month, which has the same specs as as a base one but with the i7 processor and a additional 16 gigs of ram, I have found one issue, slow mission control, but I think this issue will be fixed once Yosemite is more mature.
I used to upgrade my computers about every 18 months in the 1990's and 2000's, but now I don't see it being necessary for what I use them for, and I've been using the same computer at work, an original i7 PC desktop, for 6 years. My late 2009 iMac i5 was more than good enough for my home office but I really wanted a retina screen. I don't do any video editing but I do run many programs at once including Dreamweaver, Photoshop, MS Office, a couple of different web browsers with 3-15 tabs open at a time, a couple of RDP sessions and screen sharing sessions.