Yes, they sure are.
It's amazing how BAD some of the DVD players on the market are. The de-interlacing bugs are pretty darn awful on some of the players.
You can look at DVD player reviews in magazines where they put up a test pattern and measure the sharpness and color balance. Big deal. What really counts is how well they decode the DVDs in your collection and whether or not there are any bugs in the MPEG decoders.
The articles I linked are the only ones which really "tell it like it is" instead of just going through the motions. Stacey, Don, and the rest of the gang at hometheaterhifi.com are really top-notch techs. They know their stuff. Read and re-read those articles until you really understand the bugs in these players.
My quandary is that I really want the RP56 because of its image quality. The DCDi feature makes it so that when there's a bad cadence break in a film, even when the player drops to video mode, you don't notice it.
Unfortunately, I can't have the RP56 because my widescreen television is a generation too old. When I feed it a 480p signal, it locks into anamorphic widescreen mode. Well, that means I'd have to manually switch the player to interlaced mode in order to watch a non-anamorphic disc.
The JVC players, on the other hand, have an auto-scaling feature which makes the movies play at the proper aspect ratio without me having to do any intervention. So I'm seriously considering one of the JVCs...