I recently got the Dell 42.5" 4k monster (P4317Q), and while the dpi and color reproduction aren't good enough for serious design work, I'm able to divide my desktop into thirds for browsing and text editing. I usually keep a browser on the left, documentation in the middle, and a terminal on the right. I still get a little giddy when I turn it on every morning. What I really want is for apple to start producing 42" 8k "retina" screens, but I won't hold my breath. :)