Got my 50HM66 delivered today and have had a couple of hours to play with it. First off it's a very nice looking TV. That's important to me anyway. The screen just about fills out the whole TV. You see all picture and very little (maybe 1.5 inches) bezel surrounding it - I like that. Fairly decent remote too. I like the picture size button. Also has a direct input button. You hit input and press 0 through 7 and it goes right to it. O is for the antenna/cable. One thing I did not realize is that it does not support TV Guide. Bummer. I have it hooked up with a cablecard and I don't get any listings. My previous Samsung and RCA both had it. A found a quirky issue with the stretch modes. On analog channels Theater Mode 1 is very good. However, if I go to a digital cable station is looks like it turns into a zoom/panoramic stretch which is bad. But in TM 2 and TM 3 it has a scrolling function that allows you to increase the stretch or decrease it. Not for TM 1 though, which would have been nice. You can use thee stretch modes in HD, but I don't know why you would want to. For now, I'm keeping it in full mode so I don't get a discrepancy in the picture going from an analog station to digital. Geometry on the side bars is very slightly bowed. Noticeable, but not too annoying - I can live with it compared to my Samsung which was really bad.
I did not calibrate it so I'm viewing an out of the box picture. The analog PQ is fairly decent. Better than both my Samsung and RCA (both DLP's), but not as good as my 64" Pioneer CRT. Very watchable on my cable system (Wide Open West). The digital channels are naturally better quality. That stretch mode issue bugs me a little though. I don't get why it does that. My RCA did not have that issue. Actually, it had a very good stretch mode.
I have a Panasonic 97S hooked up via hdmi and sampled legally blond 2 (not a great transfer) and Spy Kids 3 (not the 3-d version). It handled LB2 well and SK3 was very very nice. Excellent detail, very bright colors, little to no MQ noise. DVD's on a half way decent player will be a delight on this set.
Finally, the HD picture. Superb. Right now I am watching Shark Tale in HD and (I know it's animated) the colors are phenomenal. Blacks look very good. I'm very impressed. Just saw a promo for Herbie and Lindsay Lohan's skin tone looked good. Skipping around the HD channels and at times I see a tinge of red, but I haven't played with the settings much, just turned the contrast down to 60 and backed off the sharpness some. Out of the box skin tones are very acceptable. I am very impressed with the smoothness of the picture, much better than my Sammy and RCA.
I would have no problem recommending this TV to a friend and I think that's the real test. Now, that said, I know the majority of AVS members probably consider themselves video/audiophiles so you may be more critical than me. However, I've looked at a lot of DLP's in the past month (returned both the RCA and Samsung - thank you for your return policy Best Buy - I know BB takes a beating on this thread but they guys there were very accommodating and friendly - no I don't work there!) and the PQ on this set rivals anything I've seen. It's a keeper.