This seems like a pretty good adaptation for the mini-series format. The figures are clearly drawn, for people who came in late. The action is well paced, to keep people coming back. The characters are bold, and mythic, the way Herbert drew them originally.
The script-writer has taken some liberties with the story. Well, some were needed for a successful screen play. The original books were masses of subtle and interlocked detail, way too much to convey on screen. If a few points were lost in the translation, it was because the TV series is a different dramatic language than the book. A few points were enhanced, too. Irulan, for example, is much stronger on screen than I remember her in the original. Perhaps her additional presence isn't 100% authentic - if so, I consider the difference very tolerable.
There are a few points that didn't work for me. I'm not sure why the imperial soldiers wore their coloful dress uniforms into the field, for example, and the sword-vs-gun battles were a little hard to swallow. The color schemes were a bit florid, as well. Intense, ultramarine blue lighting meant "night", even when background lighting was of other color. Tangerine orange encoded the desert scenes, and so on. Some of these problems were fixed later in the series, but jarred in this set.
It's watchable entertainment, and doesn't demand too much of the viewer. It's a bit long to watch all at one sitting, but was never intended as a single endurance exercise. I won't be giving this one away, but I won't be rushing back to it, either.