Got my Oppo 971H this morning. To sum it up, it has a lot of nice tweakable features that other players don't, like the various zoom levels, region free, ability to play DivX and other formats, etc, but in terms of playing DVD's it's not that special.
The TV is a Panasonic TH-42PX50U plasma. The Oppo is connected to the TV's HDMI port with the included DVI-HDMI cable. The sound is connected to a Sony STR-DE898 receiver via optical PCM cable. My other DVD player is a Sony DVP-NC80VB 5-disc changer connected to the TV's component inputs and to the receiver's coax PCM input.
I was impressed with its region free feature and its ability to play PAL properly. I did the "setup - 9210 - 0 - setup" sequence to make it multiregion, and made sure to set the player to Video 2 so that it would handle PAL correctly. Then I put in the Region 2 PAL version of They Live. This looks really good on my plasma. Absolutely no issues with sound synch or frame skipping or anything like that. I had previously used a Cyberhome CH-300 to play Region 2 / PAL discs and those were definitely a problem. So the Oppo is a very good player for multi-region DVD's.
But in terms of PQ improvement over the Sony changer, there pretty much is none. I played the Imax version of Apollo 13, and there is very little difference between the Sony's and the Oppo's 480p. Likewise, 480p and 1080i on the Oppo pretty much look indistinguishable. 1080i is perhaps a hair sharper, so I'm leaving it on that setting for now. Admittedly, in my case, it is possible that the PQ similarity is due to the TV. The TH-42PX50U is a 1024x768 display, so no matter what the input resolution is, the TV has to rescale the image to fit. Surprisingly, 720p is rather poor, but I've read that the Panasonic's 720p input support was tacked on at the last minute and it actually displays in less resolution than 480p does. So I suppose it's conceivable that if this player is used with a TV whose native resolution is true 720p or 1080, it might make a real difference, but on a plasma I don't see it.
There were a couple of minor things that bothered me about the Oppo's display. It seems as though there is sometimes a bit of yellow ghosting, sort of like a Y/C delay issue, around vertical edges in some scenes. Also, the image seems a bit softer than that of the Sony, regardless of the resolution I set it to. I will try playing around with cross-color correction, true-life, and sharpness to see if these can be improved. Right now I have tru-life and cross color correction enabled, and sharpness, brightness, etc, at the default 0 settings.
I really have nothing to say about the sound processing quality, because I used the optical output to my DTS-capable receiver and set the output to "Raw". So the player does no processing to the sound, and the sound is just as good as with my other DVD player.
Overall, and this is just based on a first impression after playing a couple of discs, I don't regret buying it. It's definitely a lot nicer than any of the cheap region-hackable players like a Cyberhome CH-300 or the various Daewoo ones. The additional features are pretty compelling -- short of a HTPC there really isn't anything else that can compare in terms of versatility. And the PQ is certainly not any worse than any other player in the same price range. But the scaling really does nothing to improve PQ over a good 480p player.