If you're looking at the specs, there are other computers out there that have better components, but I do think its a great computer.
Of course, if your demand doesn't need anything beyond what the iMac can offer, and you have the extra buck for the apple brand, it's a great computer. I was very happy with my iMac, except some lack of performance (throttling and overheat), games and some of the software I use more and more that is Windows only....all of this made a new Windows machine a better option for me. And, I think actually the fan noise and overheat bugged me the most overall, doing rendering and such made my machine noisy and useless while working.... But if none of those apply and you can snort out 4000 USD then its a nice machine.
But, Apples negligence to touch on OSX, claiming its a useless feature and the fact that the iMac hasn't had any design improvements in a decade, isnt great just because it allready has a nice design...imo. The aluminum minimalism is nice, the machine still looks good. But the lack of ergonomic features, noisy on high rpm and under powered fans, the problematic input on the backside, and lack of touch is in my opinion things the iMac can improve on. Especially since I'm a professional artist, touch and pen capabilities is something I think would be useful.