I've purchased U2414H (rev00) monitor a few days ago. I must admit I do love its design and features, but there are some really annoying issues, which are completely ruining usage experience.
First and most annoying one: when I drop display's brightness below 30 percent, the backlight starts flickering with a very high frequency, the lower brightness setting is, the noticeable flicker become. As web-developer I work with text editors most of the time, and even 30 percent of brightness is too much, I'd like to keep it about 10-15, but flickering strength at this brightness range makes my eyes suffer.
I feel frustrated, because one of the main reasons I choose this monitor was Dell's claim that this monitor is PWM-free.
Second serious issue is a limited range RGB issue with Nvidia cards, which is described in this thread.
I'm running U2414H hooked via HDMI to the custom-built PC with Nvidia GTX760 graphics card. OS is a Windows 8.1. I tried to perform a factory reset as well as to use DP connection with supplied cable - flickering issue is still there.