It's a big deal.
For me, someone who watches lots of movies, the greys, blacks and shadow detail aren't good enough yet - they're better on SOTA LCDs like Sony XBR and Sharp, but they're not quite good enough yet for me. Plasmas still beat LCDs hands down for shadow detail and deep blacks. My other hassle with LCDs is the viewing angles.
If you're not a movie watcher then you might be very happy with an LCD.