A few weeks ago, when I first got my HL-S 6187W, I liked it a great deal, but was bothered by a few things: 1) The colors were noticeably off (blue was way overemphasized), with no obvious way to correct them, and 2) the set was merciless to poor sources, emphasizing every flaw. On the whole, I found it superior to my two-year-old Hitachi 57S500 CRT rear projector, but there were certainly areas in which the Hitachi was better.
Since then, I've had the set calibrated by umr, and picked up an HD-DVD player for myself.
Revised opinion: Well, wow. There's no longer any area in which the Hitachi is better, except for the UI (the Samsung doesn't have discrete inputs on the remote, doesn't have night/day modes (you can fake it, though), and is just more awkward in general). This is the best picture I've ever seen on a television.
I was a bit nervous about the calibration, because... well, people say that it makes a huge enormous difference, but people also say that about power cords, so clearly people are full of it a lot of the time. Honestly, if the TV hadn't had any flaws that were outright visible to me (as the weird colors were), I probably wouldn't have bothered with it.
As it is, I'm glad I did. Not only did Jeff fix the colors (which, because I'm a total geek, was remarkably entertaining as a process), but he mucked about with the brightness and some other settings. The result is a picture that looks much better on every type of program material -- colors are way more accurate, MPEG artifacts are less noticeable, some banding that I'd noticed before is gone, and there are way fewer rainbows than before, as a result of the reduced brightness. It seems weird to say, "Yeah, I paid somebody to make my TV dimmer and get the colors less vibrant", but hey. I thoroughly recommend a calibration by umr for anyone with this television, as it really is just way off out of the box, and there's no way at all (I can definitively say after watching him make adjustments for four hours) for a normal person to get it fixed up right.
As for the HD-DVD player, well, it's just plain ol' the single best source I've ever seen, darn near flawless, and with amazing detail on this display. Watching Serenity on HD-DVD on a calibrated 1080p Samsung is just an amazing experience. This is about as close to a film experience as anyone's likely to see until... well, until next year's models make the current stuff look like crap. But for now, it's seriously impressive.