It seems like most of the complaints about this monitor are the result of its interaction with Nvidia cards and/or a crappy cable included with the display. What's your personal experience with it been like? What are you connecting it to? Have you tried a new MDP to DP 1.2 cable? What rev did you get? Where and when did you buy it? If it's working, I'd keep it. If it's buggy and a new cable doesn't help, I'd definitely return it and either save my money for something better or rebuy from Amazon if you want another roll of the dice. Either way, interested to hear the outcome. I've had my eye on one of these, but the more I hear, the more I'm happy I resisted the temptation. But perhaps it's better than reports would indicate on the Mac Pro (with AMD cards) or the nMP in particular.
I've just set it up tonight and I just used my color calibrator on it. I barely got to play with it, take what I say for what it's worth. Also I have an LG 34UM95 along side this for reference.
I ordered from Dell on the first of the month, and I'm happy to report that I received a A01 revision which should fix all the issues reported. I've connected it to my nMP with the DisplayPort to mDP cable that it came with. The only thing I had to do to get it on native res and 60hz is enable display port 1.2 in the monitor settings. I can't imagine anyone using 30hz honestly, the mouse was so choppy.
As I mentioned, I used my color calibrator (i1Display Pro) on it. It seems that the monitor is pretty well calibrated by default already, the only thing was that the brightness was very high by default. Oh, inside the package there is a factory diagnostic sheet that shows basically the monitor passes all the factory specs. This is the first I've seen this included in a new monitor.
Overall, my literally 30minutes impression on it is pretty good. Color looks good, looks like mavericks detected this 4k monitor so I shouldn't need to do RGB override on it. I haven't decided if I want to use the scaling on it, I think I might have to. I'm typing this message on it right now and my eyes are straining to read the words as I type.
Personally, I definitely need to get a ergotron arm stand for it. Biggest complaint is that the stand doesn't adjust very tall. Though, I think the stand should be sufficient for most people, it's not that bad.