I briefly went to a 4K 24" - I ended up returning it because of a manufacturing flaw, but I was not very happy with the overall experience (on windows 7). Perhaps on a 27 or 30in this is less of an issue, but I was noticing some applications scale well and some don't. If you use everything in native its tiny, if you scale that is where you encounter issues. Chrome was particularly bad because I zoomed in to like 150% on sites, but the tabs and url bar was tiny. This was about a year ago so perhaps things have gotten better.