Can't subscribe to that. Cube itself was fine. Only OSX and some (mostly professional) 3rd-party apps for it where unoptimised in the beginning. With some updates to major components you could extend the useful service life of the Cube easily to 7+ years.
The Cube is far from being comparable with a mini, because you can (very easily!) change nearly all key components (CPU, GPU, RAM, Harddrive), which the mini can only dream of.
To me the iMac is first and foremost a monitor with an attached computer in a nice packaging. You could as well bolt a Mac mini-(or even NUC-)sized computer on the back of a standard monitor and get a similar performance and usability, only in a not-so-nice looking package (well, if you look at the back - it'd make no difference when sitting in front of it).
An iMac will never be able to be as versatile as a well-designed headless Mac, because the monitor housing severely restricts thermal management, leading to annoying fan noise under load. Granted, i may be spoiled by the MacPro 1,1 I had: Where the iMac is silent under idle and low-demand conditions, the MacPro emits an audible, yet not obtrusive hum. But under load the MacPro hum stays at the same level for a very long time, where the iMac roars like a jet engine after a few minutes.
Even the older, much bigger flat-screen iMacs eventually showed problems with heat management, leading to visible impacts on the monitor part. I'm looking forward to long-time reports on the anorexic iMacs of today.
Also multi-monitor settings are not as easy to accomplish with an iMac and its current design effectively renders internal updates impossible (the exception of Ram updates on the 27" just reinforces the general rule).
Edit: Sorry for having become completely off-topic now ...
