I've got the LG alongside my NEC 24WMGX3 and to be honest it's pretty much night & day in terms of overall image quality. The NEC is (as would be expected) far superior in every way, shape & form when it comes to general Windows/Office/Internet use. Even using the same settings as FlatpanelsHD used in their review with the LG, it still looks washed out and overly sharp in comparison. Having said that, I improved the sharpness issue which I think may be caused by Overdrive by reducing Sharpness from 5 to 3. That gets rid of the 'halo' / glow around fonts / icons.
However, when it comes to gaming the LG really excels. Motion is very, very smooth and input lag is non-existent. Even though the LG is slightly smaller than the NEC and the image quality isn't in the same league, in my opinion it's pretty much the best bang for buck gaming monitor available. My brother also has the LG and he's delighted with all aspects of it. I bought the LG after seeing my brother playing Bad Company 2 on his. It's as close to a CRT as I've seen when it comes to responsiveness.
I probably wouldn't be so harsh on the 2D performance if I didn't have the superb NEC sitting right next to it.
Also, I haven't tried the 3D mode at all because I'm not really interested in it. I just wanted 120Hz and a fast gaming TN panel because the NEC ghosts pretty badly when it comes to gaming.