as far as i can tell, i did not detect any kind of lag, ghosting or shadows whatever (probably i'm not that particular about graphic - as long as i can play my games and the graphic is acceptable, i do not care)
so all i can say is, it is a good monitor but it will suffer the same problem like any other lcd monitor - backlight bleeding.
below is a picture taken when i got my replacement monitor from dell. the left is the new monitor that i got, and the right one is the old monitor (i used it for less than 3 weeks)

notice the difference? and right now, this monitor suffers the same problem. it can be a bit irritating when you watch movies and the screen should be all black but because of the backlight bleeding, you see some white spots. (you should expect this when the contrast ratio is 1000:1 and as far as i know, no LCD monitor have contrast ratio larger than 2000:1)
i still consider it a good buy.