[Bassnut (Fred)]

I have a Dell 27" 4k and I have a bit of trouble with it. This forum and almost all apps are fine, they size up much the same as on any 27" monitor so I wont bother posting screen shots, but text is much smoother with the higher res. Only apps designed for 4k such as PS, LR and other graphics/video apps make use of 4k res in the presentation of images/video and menu/text size etc is settable.
The windows start-home screen (with classic desktop shell) has really tiny text and program icons by default, and I have found windows settings for this to be unreliable. Sometimes the PC powers up (win8) with default tiny text/icons, and sometimes larger with settings I have adjusted in windows. Icon positioning gets scrambled with each change of course. Im am used to this now, is not a deal breaker, I can just read the tiny text, no other app I use has this random problem. It might be a driver issue with the Dell monitor on power up.

Although most apps just look the same as on a normal 27" (but allow much more zooming out so more readable data shows, such as excel ), Some apps have problems. MYOB did until a recent update, CCD stack wont show many option pop up windows, I have to use it on a 2nd lower res screen.

The worry you have with small text I had too and is fair, but it occurs rarely as a problem and is usually reconfigurable within apps that utilise 4k. Im happy with 4k with the likes of PS and processing/watching video, its a big improvement.