To start off, this screen is one of the best LCD screens I have seen. They are as sharp as the latest Sony screens (which are very impressive) but are much more black.
Even though the LCD is MORE BLACK then the Plasma (insane I know), next to the 42" top of the line Plasma of Pioneer it is not in the same league, (even when turned off, the LCD is more black then the plasma, but note, it also has a glare of blue)
If a picture has bright spots (overlight) (such as in foreheads of dark skinned people) a lot of detail gets lost (as in all LCD screens) where in the plasma there is still a lot of detail present.
But when you crank down the contrast, power up the back light and turn off all the overdrive features it actually reveals a very good screen, where maybe with a bit less black, you get an enormous amount of details and it actually is almost on par with the plasma.
Of course LCD specific quirks are still present. The screen is much more sharp so its also less quiet to look at (more artifacts on non-hd sources/less forgiving) even though it spots 100Hz and the 24 frames cine mode. Considering colors it gets pretty darn close to the plasma but still can't bring the warmth a plasma can.
For build quality it feels and looks a lot better then the plasmas. The Plasma screens feature a cheap looking plastic frame (shiny and bobbly) but the LCD is sharp and neat looking like brushed steel. It's also more heavy then a similiar sized LCD screen and at 220 watts it consumes more power then most other LCD screens (Samsung 37" grosses around 185 watts and a Sharp around 160watts)
Overall its probably the best LCD screen I have seen after some tweaking in picture quality. The build quality is very good overall and this is truly beautiful work by Pioneer.
The panel is made by Sharp (which doesn't even uses this panel in their own TV's in the west) and the ultra black looks very good. Some people say it's more reflecting then the plasmas, this is NOT true, it's more black then the plasmas, so it looks like its more shiny. When viewing they are very much the same.
Best you can buy for a very respectable price fitting in the Plasma range.
If you are a movie lover, go for the 42" plasma, if you also love to play some Xbox, PS3 or connect a PC to it (affraid of burn ins) or are a Blu-Ray lover (read, you get a hard-on from watching 1080p instead of 720p) go for the LCD. It rocks.