I picked up a LC-70LE640U at Sears yesterday and I'm happy I did. I expected to be 'just happy' with the picture quality as this isn't a high end model by any means, but I'm extremely happy with everything to do with this TV. I recorded an HD NFL game so I could compare it to my previous TV and full speed passes, running, etc are nice and sharp.
I slammed in SilverFox1's "Standard" settings as well as N3W813's "Movie" settings. Both improved the colors and overall feel over original settings. I did a bit of tweaking of both to my taste.
Sources: DirecTV HR34 (HMC), 1stGen PS3, 2ndGen AppleTV. Through a Denon AVR-2113CI receiver. I just wish I had a newer PS3 that had HDMI control. Running on latest Firmware.
Here's my really quick picture quality/source format review:
PS3/BluRay - Dark Knight 1080p - F'ing awesome.
DirecTV/HD - NFL Football 1080i - Very sharp, occasional artifacts that are barely noticeable.
DirecTV/HD - various TV - Looks great. very happy with the quality.
DirecTV/SD - various TV - Surprisingly good, obviously not HD quality, but not as bad as I expected it to be.
2ndGen AppleTV/Plex Client - Streaming Movie 480p source - VERY good quality, I couldn't believe how good this looked with only a 480p streamed source.
Sharp/DLNA - Streaming from Plex server (480p source) - Picture quality good, but couldn't find a way to change the audio track to the 5.1 track. Because of this I'll likely not use this feature over my AppleTV.
MacBook Pro - Airplay Mirroring to AppleTV - Good quality, watched a couple youtube videos that looked good.
Hope this helps those of you trying to decide whether to go for it or not.