I have to zoom web pages to be able to comfortably read anything, and that doesn't work very well. Everything else in the OS is just way too tiny. Menus, windows, etc.. I guess it depends on how close you sit, but mine sits at the back of my desk which puts it about 3 feet away from me. The whole interface is just way too tiny at native res. Apple has acknowledged this is why they're working on resolution independence. I just wish they'd be a little quicker about it.
It's not just reading. I don't like all of the interface elements being so small. Here are some screenshots I posted in another thread, 2560 vs 1920 looking at the same content. I much prefer the dpi of the 24".
http://img237.imageshack.us/img237/4530/screenshot20100215at711.png
http://img148.imageshack.us/img148/4530/screenshot20100215at711.png
If I needed the extra real estate, a 2560px display would be better, but the 24" is just about right for most use. And while I like the panels in the new iMacs, I like 16:10 better all around.