LCD blacks look better in a bright environment, Plasmas wash out when there are high levels of ambient light.
In a dark room, the opposite is true. It shows off how poor the LCD blacks are in comparison with the Plasmas.
Samsung have LED backlit displays that can display "true" blacks even in a dark room. They do this by "cheating" however. Due to how the LEDs work, they can be turned off in different sections of the display, so if anything is showing black, they just turn the backlight off. This means that, with a full black screen, the black levels are perfect. However, with actual pictures, the blacks are no better than a normal LCD.
The Kuros have, by some margin, the best black levels out there for a flat panel. However they're still not that great when compared to a CRT.