Pretty sure this new iMac's screen is delicious, but I'd have some reservations about whether or not it has enough GPU horse power to really do it justice. When Apple first released iMacs with 2560x1440px IPS panels, they looked great but the performance of the first iteration was meh.
5K display paired with a GPU with 2GB.... what a joke... thanks apple
In my experience, to run 5760x1024 (for gaming) sometimes a single r9 290x can't get the job done and you need two....