I see some people saying they have it. How hard is it to do and how well does it work?
It's no harder than flashing any GB or FroYo ROM, so if you know how to root your phone and flash a ROM it's incredibly easy. If not I'd suggest you learn at least a little bit about rooting and ROMs before you start getting into it, reading through this forum is a great way to do that.
Some builds work better than others but they're all pretty functional.
I haven't been using my DX much lately so I can't comment on the current state of any of them, but my favorite was always Gummy. I tried Liquid Smooth ICS on my Razr and it was okay, and I know there's a build for the DX. CM9 and AOKP are also solid. You can find them all in the Droid X ROMs section.
Mae sure you're on the .602 or .605 GB kernel when you flash them or you'll end up bricking and need to SBF.