After some frustrations trying to find a good LCD, I pulled the trigger on a 46 inch ST30 yesterday.
Got it home and immediately got my satellite running on it. I was immediately struck by the smoothness of the picture, but then I noticed that the "motion processing" was on by default. So with that turned off it's still very smooth, but not as perfectly smooth as I would have expected. Panning shots in various shows still showed the slightest touch of stutter to them. Still noticeably better than an LCD without motion processing turned on though.
I then loaded up a PS3 game called Joe Danger. It's a fast moving racing/action game, that moves like an old school videogame Excitebike. As I was playing I kept noticing this odd artifact on certain edges of objects. It almost looked like what you'd see if you looked at a 3D image without the glasses on. But it was only on the edges of certain objects. Then I loaded up Call of Duty: Modern Warfare 2. I started seeing the exact same thing on some edges, and then it dawned on me. I'm seeing "green phosphor lag". Anytime there was a bright object moving quickly it was be noticeable on the edges. I was seeing it everywhere playing Call of Duty.
Regarding the specifics of this ST30. Just as it was mentioned in CNET's review, only the Cinema picture preset has remotely accurate gamma. Every other setting was way off, and the blacks were crushed. I played with it a bit, and it became very apparent that just as the CNET review mentioned, I would only ever use the Cinema setting with this TV, as all the other presets were not adjustable enough to fix this gamma problem. The only problem with the Cinema setting is that it's max light output is kinda low. Fine for a dark room, but if I ever wanted to open the windows a bit on a nice day it wouldn't be so good.
So after a couple of hours it became clear to me that I wouldn't be happy with this TV. The green phosphor issue was not something I could get used to, or accept. It also bothered me that Panasonic intentionally gimped this TV by only giving it 3 HDMI inputs, and one of them are on the side, where the cable sticks out when plugged in. It's annoying when companies just intentionally gimp a TV like that. Panasonic is offering 4 HDMI inputs on some of their much cheaper LCD models, but they decide this 3D plasma should only have 3?
I wouldn't consider the GT30 because of it's floating blacks, and I won't consider any of the Samsung plasmas because they buzz and that is a no no for me. Although this ST30 did buzz a bit, contrary to what some people said in this thread, it was certainly quiet enough to be acceptable to me.
So I just don't think I'm a plasma guy. If I were just into movies and TV viewing, I very well may be, but with games being my primary focus, the green phosphor and the worry of burn in are enough to push me away.