And utter dogshit to troubleshoot and fix when they're not. Both of mine - a white one and an aluminium one - had serious hardware faults. Both fixed under AppleCare.

When you get a Mac fixed under AppleCare you get an invoice listing all the parts and their prices, even though it's at zero cost to you.

2nd iMac needed:

Screen replaced - £600
GPU replaced - £400
Optical drive replaced - £150
Hard disk replaced - £100

First one had something similar. I wouldn't keep an iMac beyond the warranty period - they're both expensive to fix (parts are just ruinously expensive) and difficult to work with; they're hard to open with several points of expensive failure in the process.

If Apple simply stopped the pointless quest for thinness on desktop computers, they could use nice, pretty-much-stock desktop-class components with quiet, effective cooling solutions, in a serviceable form factor. And it'd still look awesome.

But at present they're a chimera - odd sort-of-laptop components in a thermally-compromised enclosure that positively encourages failure and is an absolute bugger to deal with when that happens.