I just got the TC-L55ET5 today. Exchanged a 55UT50 plasma for it through Amazon. I had the plasma for a couple weeks but couldn't live with the buzz that I could hear 10+ feet away over dialogue in bright scenes (a tech came and changed out screws--didn't help) and was starting to get annoyed by IR from games and ESPN. Amazon was sold out of the UT50 so trying another wasn't an option, and I was pretty sure Plasma just wasn't for me since I have a brighter room, watch hours of ESPN and play a decent amount of games.
After a few hours (TV was delivered around 10am) with the new set, I'm very happy with it. Completly silent, not buzz at all. Picture is awesome. Blacks and motion aren't as good as on the plasma a expected, but colors pop much more, the set is much better with my blinds open (though I still wish the screen wasn't glossy) and the 3D is surprisingly clearer. I expected the 3D to be worse being passive vs. active. But it looks better to my eyes (less double image/blurring of things far forward in the field). And I love not having to mess with batteries, turning glasses on etc. Picture uniformity seems solid, minimal light bleed in the corners as best I can tell. I'll preface all that by saying I"m not a videophile type and won't spend much time looking for problems.
I tuned the picture settings using the Disney WoW disc, and this is what I came out with.
Picture Mode: Cinema
Back Light: 25 (just left that where it was)
Sharpness: 25 (didn't seem to make any difference to me turning it up or down (everything is hooked up via HDMI through my Denon 1312 receiver) so just put it at 25 fairly randomly
Color Temp: Warm
Color mgmt: off
A.I. picture: off
Video NR: Off
Aspect Adjustments: Use Size 2 so you aren't losing 5% of picture with overscan in Size 1
HDMI Settings: Content type=Graphics
Block NR: Off
Mosquito NR: Off
Motion Picture Setting: Off
Black level: light
I'm using those for 2D and 3D now (have to set 3D seperate--display 3D content then go into the picture menu)--both look great to me. The glasses don't seem to darken the picture much in 3D, unlike on the plasma where I had to bump contrast some for 3D.