After watching Lonesome Dove religiously since the DVD was released in 2002, I can honestly say this is like watching a brand new, never-before-seen series. While I won't say this is something of reference HD quality, I will say it's a justifiable upgrade to the DVD version and so much more.
To begin, let's take a look at Tommy Lee Jones below. The detail on his beard is instantly noticeable. In fact, this scene where Call, Gus, and Newt are having breakfast, brought me closer to the characters.
Below we have Jake Spoon feeding his gambling addiction. The purple shirt Robert Urich is wearing, really comes across as one of the best shades of purple I've seen.
The scene below was just meant for widescreen viewing. Comparing this to the 4:3 (fullscreen) version, there's just no comparison. And with scenes like these, the larger the HDTV (or projection set), the better.
I remember this scene had Diane Lane's dress cut off on the right, and just seemed like she should be further left. Well, my intuition was correct. However, the lower portion of the blanket is cropped. Overall, a necessary sacrifice. The clouds in the background also look great on a larger HDTV (50" and higher). You can really see some depth to them. On the 1989 version, it was more of a gray smear.
Finally, this is one scene which demonstrates the reason why HD is a must. The house's edges and shape is much more detailed, the horse and buggy is more detailed, the prints on the two girls' outfits are more detailed. Everything is just more clear and this adds to the realism of the movie.