Definately a great game for its time, well written and well developed.
The game follows a linear plot, which means that each time you play, the story is going to be the same, and that every difference between one game and the next is made by you and your imagination. Imagination, it is one thing that old videogames stimulate, instead of supress like modern day GTA et al. Don't mistake me, I enjoy GTA very much, but it will never have a place in my heart like Dune.
There are a few downsides to this game, the very slow Orni travel times can make exploring to find new sieches very tedious. This is very evident if looking for ones that the game does not direct you towards. All in all though, these unknown sieches will never give you more fremen troops, just a few pieces of krys or a wierding module.
The story itself generally follows that of the book, not to any large degree, but enough to keep most fans happy. It would be nice if there were different missions/campaigns to be played, but hey, it was only 1992, you can't ask for too much. That being said, most newer computers will not like to run older games, this one included, so if you have an older computer lying around, don't trash it just yet, hang on to it so you can play some fun old games.