Pretty much what Khaid said. TN panels have fast response times and they're cheap, but some of them are just dreadful when it comes to viewing angles, so they absolutely suck if you slouch.
I'm a big sloucher which was my concern with the TN panels. Some do alright but I didn't want to buy one unseen and find out I don't like it. Sam's Club has some Samsungs that are horrible. I couldn't find the sweet spot anywhere when I was standing in front of them. The U2412M has a 178' veiw angle.
Well I've been using the Dell UltraSharp U2412M for a day and I'm pretty happy with it. It's every bit as good as my last monitor and I can hardly tell the difference between the MVA and IPS panel. The MVA might have been more saturated but that was a long time ago before the lights went dim. It's using about 26 watts compared to the 65 watts of my LCD and it doesn't put out near the heat. The stand is fantastic. It's a heavy steel core with height adjustment, cable management, and 90' rotation. The USB hub is a nice bonus. The exterior looks sharp from the front or back. The view angles are very good but perhaps not as good as the MVA. The contrast however is awesome. I guess that is to be expected with a new monitor. The on screen menu is the most brilliant one I've ever seen. I was actually expecting to be so hard that it took me a while to figure out it's simplicity. The buttons are all soft keys which get reassigned depending on which menu is active. There is a menu next to the buttons that indicate what each one does at any time. As far as negatives go I would say the anti-glare is a bit aggressive. Right now reflection is not an issue for me so a little more color pop would be nice. There is an "IPS Glow" in total darkness but that doesn't bother me at all. I suppose it might bug someone who watches a lot of movies.