Someone gave me a 46" 6420 as a Christmas present. I assumed that it must have been a cheap model (or at least on sale for a great price) for it to be given to me as a gift, but so far, it's a nice TV. I haven't looked to see how much they sell for. My dad has a couple Samsung LEDs in his house, and those two are my only other exposure to the technology. Before reading anything about them, I found that the dimming function was very pronounced on the set in his kitchen, but I never noticed it on the set he has on his screened in porch. I actually spent about an hour going through the menu trying to figure out how to disable it (I figured it was some kind of dynamic "enhancement" or power saving function. Glad you guys cleared that up for me). I set the shadow detail to +2 a couple hours after unboxing mine (just calibrating by eye, no knowledge of what I was doing) and for that reason or whatever other, I haven't noticed any dimming on my set. I've been using it as the display for my Mac Mini, watching 1080p Blu Ray rips, 720p NTSC television, and SD NTSC and PAL television. Also a few Brit movies, which I assume were ripped from a PAL format, but I don't know. I worked with professional home theaters installers about a decade ago (I'm not certified or anything, just worked with a few guys who were), and have been exposed to lots of properly calibrated, high-end displays. I'm very critical of most pictures I come across. Haven't had much contact with the HT scene in years, though, and am definitely out of touch on the new technologies. I just watched my first two 3D movies at Thanksgiving (Avatar and Toy Story 3). Watched those on some high-end Panasonic plasma my dad has. That Panasonic (I have no idea about model numbers, I had to find my user manual to figure out what model I had when I logged onto the forum) is one of the best flat panel displays I've seen. Tons of depth and texture in the 2D images. I don't know enough about 3D to comment on that aspect. So I've been comparing the Samsung to that picture as I break it in. I assume there's probably a few thousand dollar price difference between them.
Anyway, the Samsung has a pleasant picture, in my opinion. I do feel like alot of black textures (clothing) are being crushed, but that's always been an issue with flat panels aside from those Pioneer models a few years ago (as far as I know...again I'm out of touch). The colors (particularly skin tones) looked better than average to my eyes after just a few minutes of tweaking by eye on a movie. Occasionally I feel like the image becomes too artificially sharp, even with the Sharpness on 0. I noticed this on my dad's Samsung in a huge way when I saw my sister playing her XBOX on it. Using it as a computer display with tons and tons of text, that's probably much more apparent to me than in most situations. Messed around with the contrast and brightness (after dropping the sharpness) and it's looking good enough at the moment. I spend most of my time switching around the LED motion settings, as I find it ghosts alot when watching less-than-great 1080p films. Better 1080p formats are mostly alright (I still notice ghosting much more frequently than I'd like, however, but I guess that's the LED technology in general). I played around with the 2D to 3D conversion, and it was horrible. I'm not enough of a 3D enthusiast to have my own player or 3D films. The glasses are like a third of the price of the Panasonic ones my dad has, though, which is a plus. Although after reading this thread, I now understand why they're so much cheaper.
I have AVIA and DVE Blu-Rays, but I haven't used them to calibrate yet. My dad also offered me his Disney calibration disc (hadn't heard of that before), so I'll try that as well. My calibrations thus far are just general adjustments made at my discretion while viewing. I noticed the set has a test pattern built into it, which is nice (unless it turns out to be locked when I try to use it...which I haven't tried yet). The settings I've been using for the last week or so are almost identical to the two posted in this thread. I do have Sharpness at 0, however. That's the major difference. I had turned off the LED motion Plus in the hopes of eliminating the ghosting, but after reading around the forum tonight, I've turned it back on. I use the Clear setting rather than Standard. I've used Smooth some as well. I honestly can't tell a huge difference between them yet. The Edge Enhancement definitely ruined the picture, in my opinion, so it was only tested for about twenty seconds. I was using a low contrast in the hopes of making the PC text a little easier on the eyes, but I followed the config link someone linked to earlier in this thread, and am using those settings now. The text and aliasing around icons and such isn't too bad. I was using Warm 1, but just switched to Warm 2 based on said config. I was using the "normal" HDMI black level, but just changed it to "low" for this new config. When my eyes get used to the new settings, I'll probably bump it up. I played around with the black level settings for awhile (dark, darker, darkest) but am still unsure about them. My natural instinct is too disable any "enhancements" like that, but I didn't hate the way it looked. Slightly more depth when viewing the first two Resident Evil films on Blu Ray. Haven't had enough time with the set yet to decide how much good or bad they do. I've got it turned off now. I'd say the biggest things to focus on out of the box is the sharpness. 1080p images are still very crisp and detailed with my current 0 setting (I still think maybe too sharp in some scenes). I was occasionally getting banding in black parts of the image, but I think that may have been caused by the line out on the Mac Mini. Running on a Geforce 470 PC with a mini-HDMI to HDMI connection now, I'm not noticing it. The colors occasionally seem inconsistent across the screen, but that may just be me.
Overall it's a nice set for watching 1080p films on. Standard def also looks great compared to the early flat panel sets I was used to back in the day. Lots of options. I don't know yet if that's a good or bad thing in this case. It's also crazy thin. That blew me away. Like a sci-fi movie prop.
EDIT: And just as a note, I haven't hooked the display up to a cable source nor a DVD or Blu Ray. I'm viewing with a "loaded" MPHC config on Windows, and VLC and Movist on the Mac.