I just bought this monitor a while ago, & only after unboxing it I realized that this is an upgrade from the previous model , VS239N.
VS239NR has ASCR of 80M:1 and 5ms response time
Here is the detailed spec http://www.asus.com/Display/LCD_Monitors/VS239NR/
I could say that the display quality of VS239NR is a bit better compared to my old VS239N, but not much though.
This maybe due to the higher contrast, that the black color in VS239NR seem to be darker.
I would like to hear others opinions on how this VS239NR could compete with the DELL U2312HM.
Both are IPS but VS239NR is much cheaper.
I am planning to get the 3rd monitor for eyefinity