I switched to HP ZR30w (30" IPS panel) not long ago from an old 20" Dell. The text is super clear and the space is huge.

Some people say that they use a 24" panel in the portrait mode for coding. I haven't tried it myself but one thing that I am curious about is whether their neck starts hurting. You see, if you have a text editor occupying all of the vertical space in such a setup, you cannot just move your eyes to be able to see the top and botton text. You actually have to move your head. I already feel this a bit on my 30" in the ladscape mode. That's why my emacs is not running at full-vertical-screen.