I got my Liquid Platinum back in mid December and have been really impressed with it. Objectively it runs moderately warm to the touch and is pretty much dead quite as far as I can hear. Based on comments elsewhere it sounds like a couple people have had issues with theirs, but mine has been rock solid - and Monoprice backs it with a 5-year replacement warranty.
With regards to sound, I agree with much of what was said in the Enjoy the Music review. It is pretty neutral to my ears, much more so than the Liquid Carbon. I got a 789 last Friday and the Liquid Platinum is a meaningful step up - particularly in the areas of sound stage width, separation, and overall resolution. The thing that strikes me most about the Liquid Platinum is the "out of head" experience it gives you. The 789 and other amps I have, comparatively, don't have the sense of space/width that the Liquid Platinum does. Not that the 789 and others are bad, the Liquid Platinum is just better.