Let me preface this post by saying that I dislike Tolkien's Lord of the Rings (and Peter Jackson's film trilogy). I prefer The Silmarillion (which makes me an even bigger geek than LotRs fans.)
I also dislike Riener Knizia's base Lord of the Rings game because it's too linear. I enjoy making long term plans. The simplicity of planning in the base game bores me: save travel cards for Mordor (and other simple plans).
But Lord of the Rings is one of my favorite games when played with the expansions (any single one or combination of them). Why? Because the basic framework of the "boring" game is a framework on which a fun game is then played.
By fun I mean that the long term effects of choices is harder to judge. Which board(s) to skip in Friends and Foes (is it better to go through a board than take damage from foes)? In Battlefields there is always tension about saving precious fighting cards for the main track or killing enemies to prevent damage and/or prevent damage (better to kill the double damage enemy or the one who mores the eye back).
Sauron has the dark rider to hurt the fellowship in the Sauron expansion. Picking which symbol to effect you each turn is hard. Do you go for the extra goodies on the side tracks or ignore them? There doesn't seem to be a best option with Sauron since the player can listen to hobbit strategy and adjust his actions accordingly.
Sauron seems to have a big advantage in this expansion (at least with new players). I feel that Sauron is best played by the least experienced player. This way they can learn the game without being bossed around by more experienced players. If your group is good at Sauron it is easy to handicap the game for the newbie (add another expansion, start Sauron on 10 or 12, and/or use dark event tiles).
The game is a fun cooperative game, but even in talking about it (dark events, flow chart battle boards, skippable boards), I'm not immersed in J. R. R. Tolkien's world. War of the Ring is a game which is almost impossible to talk about without LotRs immersion. I prefer Knizia's abstract cooperative game, though. It is one of the few games that I would play almost any time (it does require thought so if I'm really tired I'd probably bow out).