Ok, after finding some better calibration via tinkering and finding a post from someone else who has one and using their settings I think I got my LG 39LN5300 about as good as it will get without some sort of professional calibration. I'm just a normal guy who likes to game and don't have any of those colormeters or whatever they are called used for calibration.
I came from a I-INC 28" 1920x1200 TN LCD. I wanted to keep to the 1080/1200 res and yet go bigger screen if possible. So unless I wanted to get a 27" 1080p my choices were TV or projector. Projectors are a more expensive set up so that threw me back to TVs. I heard the LG 39LN5300 was a good tv used as a gaming monitor. I bought mine at BB but shop around because you can find them for well under $400. $370-$400 seems to be the common in store prices. Catch a sale and you might get them even cheaper.
For watching movies or anything on TV/cable the picture is quite good IMO. Gaming is pretty decent. This model tends to have a dark black but tinkering with the calibration helps and adjusting a game's gamma setting can greatly help as well. The difference from 28" to 39" is huge in games. Much much more screen real estate and fov. There probably is some input lag but if there is I'm not feeling or seeing it.
The one main downside to this TV, and its common in all TVs I hear, is the text. Compared to a gaming monitor the text is blurry or as some call it pixelated. And as all gamers know there is text in games. I'm not just talking about dialog text some character may say but also text from HUD, UI interface, and the like. I found that if I sit back 3.5ft -4ft away really helps. Anything more than 4 foot and you are no longer sitting at a desk and that is how I'm reviewing this tv. Gaming at a desk. Not a couch. Surfing the web the text is still blurry and pixelated though so I would recommend a separate pc monitor or a laptop for the web surfing and pc work. For normal gaming though the 39LN5300 is fine. You should enjoy it. I do. I'll admit up front I'm not one of those extreme demanding types. Some people get so obssed with it they become anal retentive. I'm nothing like that.
Now are there better TVs? Probably. I hear people say they game on 60" TVs and I hear plasma is supposed to be really good too. I know pc monitors are certainly better. If you are like me though and want something cheaper than those $1000+ 30" LCDs, want to keep to 1080p but something larger than 27", and okay with 60Hz, then the LG 39LN5300 is a good choice for a gaming monitor. Just remember that for web surfing and reading things in text you will want a separate monitor for that. I also looked at the 5400 & 5700 LG series and supposedly they have more input lag and ghosting issues when it came to gaming.
I'd like to buy two more of these TVs and go triple screen gaming but I need to wait until the new house is built and I have the room to do it. I'll want to build a new beefier rig as well. It has to wait until next Spring unfortunately.
I hope this little review(more of a over view actually) helps anyone considering buying this tv. You could do like I did and buy one and if isn't what you wanted for gaming just use it as an extra tv in the house. Its quite good for that. That's how i justified getting it and testing it for gaming. <g>
Edit: I game on the V354 rig in sig below and the one I use the 39LN5300 with.