Congrats on the purchase! Not my first choice in plasmas (Samsung and Panasonic are kings in this category), but I think you'll be happy with it nonetheless.
When it comes to picture quality, the rule of thumb is still plasma > LCD. All the "new technology" they've been stuffing into LCDs is to try to compensate for their shortcomings vs. plasma.
120hz and 240hz refresh rates were created to try to make up for the motion blur inherent to LCDs that aren't present on plasmas. The good is that they HAVE greatly decreased the blur. The bad is the way they do it leaves the picture with that "soap opera" or "behind the scenes/home camera" kind of effect. The footage doesn't look like it was recorded with a professional camera. This will be personal preference, but I really can't stand how that looks.
LED is merely a form of back-lighting for LCD, not a new form of TV picture/technology altogether. It is used to try and make up for the lack of brightness and contrast inherent to LCD vs. plasma. Again, while it HAS greatly improved the picture, in most cases, it STILL doesn't hold a candle to plasma.
Most of the downfalls to plasma TVs have been eliminated by now. Ghosting can still happen, but is very short lived. A few minutes of watching something else makes it disappear on its own. Burn-in, on the other hand, while still possible, is very difficult to do with today's plasma TVs. To truly burn in an image, you'd really have to go out of your way and try to do it on purpose (i.e. leave a stationary image on the TV for a day or so). To top it off, there are built in features to get rid of any ghosting or burn-in should you some how manage to pull this off. Energy wise, there are plenty of Energy Star rated plasma TVs out there (even my 1.5 year old Samsung), and they use up only slightly more energy than LCDs today. Another thing to keep in mind when looking at the power consumption on TVs is that LCDs are static on usage, where as the amount of energy a plasma TV is using depends on the image at the moment. The brighter the picture (more whites, etc), the more power it uses. When the image is dark, or the screen goes black, virtually no power is being used. This can skew some of the stats and make LCDs look like they're way more efficient then they really are compared to plasmas.
I bought my 50" Samsung plasma for $550 last spring, and I absolutely love it. Even though it's only 720p, I've left people mesmerized when I pop in a Blu-ray like Avatar or Sin City, and let them watch a few minutes of it. The picture is insanely sharp, and the colors (well...in the case of Avatar, anyway) are rich with contrast. I rarely play video games, but when I do, I'll end up playing for at least an hour (i.e. full regulation games on NBA 2k, which are about an hour each), and while I've seen image retention from the scoreboard, it's gone within minutes of flipping on the TV. I periodically use the "pixel scrub" for the hell of it, but have yet to use it because I HAD to due to burn-in/image retention. There's no question there's some glare on the screen, but it's never been to the point where it ruins the watching experience for me, even though mine's right next to a window. Once the picture comes on, it's bright enough that the glare isn't really much of an issue. However, this will depend greatly on how bright your room gets.
Some simple break in procedures for the first couple hundred hours of use. Keep the cell light and brightness levels low, as this is when the phosphors are new and unstable, thus burn in is most likely to happen. This is especially true for whites, which is why you want to keep the brightness down for a while. Don't leave anything on with a static logo for long periods of time initially. You want all the phosphors to get evenly exercised in the beginning till they harden. There's a couple easy ways to do this. If you have an Xbox, you can play music on it (I have my computer's portable back up hard drive attached to mine via USB) and set the player to full screen so that the crazy, colorful psychedelic kaleidoscope thing takes up the whole TV screen. The rich and constantly changing colors will really give the new phosphors a good work out. Otherwise, if you don't have an Xbox, or don't want to leave it running too long, you can leave the TV on the Cartoon Network. Just make sure you go through your TVs menu to "zoom in" on the picture so that the CN logo is off the screen. Again, being that most of the cartoons not only display a lot of colors, but also keep them changing at a rapid pace, it's a good workout for your TV.
Lastly, when your TV is broken-in, and you're ready to get the most out of the picture quality, hop over to avsforum.com and look up the best calibration for your model TV. There are a lot of mega nerds over there that will give you the exact run down through the menus on the way to achieve the best picture possible for your model TV. Also an excellent place to gather more info and opinions on anything home theater related.
EDIT:
ps... I have no idea why it says $2
Crap. And here I thought you were giving out $2 for input and advice. Now I typed that all out for nothing!
