i went from 1080p to 1440p and the difference was substantial, as i said before the hazro 27" was prob the most significant improvement visually/graphically to gaming i have ever made, even going 480gtx sli a year ago.
if you have the cash go for it, if your undecided just hold off a bit longer until you can afford it new cards are due soon by ati and nvidia.
Similar story went from a Samsung 24" 1920x1200 to 1440P Hazro recently and love the Hazro. It has a higher pixel density than my old monitor and everything looks better due to the higher rez.
Also given the Hazro's are the cheapest way to get a 1440P monitor you might want to review watching Blu-Ray as my understanding is the monitor isn't HDCP so you can't watch Blu-Rays on it....not tried myself.