I previously had the Maxed out 5K iMac before I switched to PC. Its not a bad computer at all. And its amazing how apple have managed to cram such a powerful computer into such a tiny case and how they have tweaked the fans to b
e super silent unless you do some heavy lifting (of course once they start spinning it sounds like the machine is about to take off). I would say in most cases the iMac is enough even for many professionals. Particularly if you work with Adobe software. ...because adobe hasnt really optimized their software to take advantage of multiple cores and good GPUs. I would say, if you are an Adobe user only I would actually recommend the iMac BEFORE the Mac Pro (even if the Mac Pro would have had new updated Xeons processor and new GPUs). Because the 4 cores of high GhZ performs better than more cores of lower GhZ. THe new PC I bought pretty much outpower the iMac I had in every way...except in Adobe programs. I made a benchmark test using Element 3d, together with DoF and glow and multiple other effects in after effects. But since AE almost only uses 1 single core CPU in the rendering process I got the same result on on my new machine as with the iMac. Despite now having the highest GhZ 6 Core Broadwell.
But, thats Adobe being lazy bastards. AE could have performed so much better - and from what I undertsand they are slooooowly working on it.
But you are right
its a laptop with a screen. Except the CPU. But laptops can do some heavy lifting.