My main reasons for buying a couple LCDs:
1: No geometry problems whatsoever. I plugged in the panels and that was it. No screwing around with any settings. They are perfectly square right from the get go.
2. No focus problems whatsoever. I spent roughly 5-6 months delaing with a brand new, POS Viewsonic P95F+B. Supposedly repaired twice, and replaced three times, every time with the same problem. Once I went over 75Hz, it would go blurry. This is a known problem with the monitor. I got so sick of dealing with it that I ordered two Dell 1800FPs.
3. No refresh/interference issues. I have a 9700 Pro and used to have the "rolling lines" issue every once in a while. As well, with running XP, it used to be a hassle using third party programs to lock the refresh rate higher. Now, with the LCD's "refresh rate" of only 60 Hz, there is no worries.
My minor reasons:
4. Less bulk on my desktop. My P95F+B got finaly replaced with a 21" G810. It was insanely huge on my desk. I definitely have the room for it, but it felt totally oppresive. I like the light "feel" of the panels in front of me.
5. Coolness factor. Not that I really care what other's think, but I think that having a dual monitor setup with two identical LCDs looks pretty damn cool.
Drawbacks:
1. Low refresh rate means lower framerates when I have v-sync enabled. I always enable v-sync as I hate tearing, but 60fps is nothing to sneeze at anyways..
2. Large dot pitch. Unfortunately, the dot pitch is kindof high. It really only bugs me sometimes, as the panels are so sharp to begin with it doesn't become too much of an issue. The same dot pitch on a CRT would be pretty unbearable though.
3. Price. This is only a minor drawback for me. Sure, I could have bought two kickass CRTs for the same amount of money, but I have had it with CRTs. The P95F+B was supposedly a pretty good monitor given the reviews I had read at the time. It really left a bad taste in my mouth concerning CRTs. I highly doubt that I will ever go back to using a CRT.