I've had my ln40a550 for one week now and would like to post some feedback, and hopefully receive some too.
This is my first hdtv. I have been mainly using setting posted by thebeginning from the calibration thread (which uses the dynamic mode.) I've also tried calibrating on my own in movie mode, using a AviaII dvd (I have an older dvd which does 480p, connected via component.) I wasn't all that thrilled w/my own calibration results so I also tried some of the 'tweaked' settings found on that thread via Cripsy (and others.) I don't particularly care for those though.
At the moment, I'm hooked up straight from the wall to the tv w/the coax. No cablebox. Actually, I recently plugged in a Belkin surge protector so the coax goes into it and another one goes from that to the tv.
I'm in Montgomery Co, MD, with RCN as the provider.
Most HD channels look great. ESPN 1 & 2, Food Network, most studio local news. Really nice.
Fast-moving action... depends. I've seen others post this same thing w/little feedback. This weekend, I watched hockey and the Kentucky Derby (NBC.) When the camera isn't panning, it really does look great. But the picture does get quite pixelated otherwise. On still shots, designs like a man's tie w/lots of close,parallel lines can look like they bleed. Hard to describe. Text can sometimes look blocky. It's mostly pretty minor but it's noticeable. I'm not sure if it's just the cable, the network, the particular show, the tv or the settings.
I also may have a minor interference issue. Occasionally, I'll see faint horizontal gray lines that come and go during various shots. It's infrequent though.
On the National Geographic channel, many shows (a lot of them) stutter. Audio is perfectly fine but the pic with stutter every few seconds. Very odd. I posted a question like this elsewhere and at least one other person sees the same thing but not quite as intensely as I do. And it's just that one channel.
I have audio going to my home theater 5.1 via a digital optical cable. But watching some shows recently, I've noticed that the audio seems to lag behind the video (or the other way around? I forget.) My receiver has instruction on how to fix this but I've not been successful w/it.