I created a special rating system for the Lord of the Rings Expansion reviews that more appropriately fits the game.  It is described here.

Example score card
Overall Score: B+
Difficulty: 
Theme: 
Fun Factor: 

Overall Score

The Overall score is a general combined grade that describes the expansions general place among the entire Lord of the Rings line.  The grades are A+ to F

When you see a + or – symbol next to a grade it simply means just a little bit better or worse then the grade suggests, but not quite enough to bring it up or down an entire grade.

A:  This is the best grade you can have, it means the expansion is among the best of the expansions in the line.

B:  This is one of the better expansion in the line, it might have some minor flaw but overall its a fantastic score.

C:  This is an average expansion, it has some elements that set it apart, but also some drawbacks that take away from the experience.

D:  This is a fair expansion, it generally has more drawbacks than benefits.

F:  This is a poor expansion, in general it means there are few redeeming qualities and it can be largely skipped.

Difficulty

This is the difficulty score of the quest, effectively a score that defines how hard it is to beat.  While generally the score assumes solo or co-op, in some cases the their may be two scores given if the difficulty is more or less depending on how many players you are.  The scale is 1 to 5 stars.

 : This is an easy quest, you should be able to beat it on your first try in most cases and it also typically means that pretty much any type of deck can beat it.

: This is an easy quest, but might have some hurdles that could in rare circumstances result in a loss.  Veteran gamers will be able to crush this quest with relative ease, new players might find it more challenging.

:  This is an average quest, one that will challenge even veteran players, but can typically be resolved by building a specialized deck or using some key strategy.  Beginners will find these quests quite tough.  Regardless of skill level or deck type, these quests are always challenging and could result in a loss.

: These are really hard quests, even veterans will struggle to beat it regardless of card pool or strategy deployed.  They require a lot of skill to beat, specialized decks, some luck and are usually difficult to beat with any consistency.  Beginners will find these quests impossible to beat and can get frustrated with them.

: These quests are all but impossible to beat.  No matter your skill, deck or strategy, most of the time when facing this quest you will lose.  It requires very specialized decks and strategies to overcome, not to mention a bit of luck.

Theme

Theme is a measure of how thematic a quest is.  This considers the Lord of the Rings universe as a whole, the link the quest has to the cycle and to the encounter deck.  It also considers the link between mechanics and the theme and general feel of the quest.  Its rated from 1 to 5 stars.

Fun Factor

This is my own personal tilt, its simply a gut call on how fun I think the quest is to play.  It typically combines all of the other attributes to a degree, but is also largely linked to how re-playable the quest is and how enjoyable it is to play.  Like Theme it ranges from 1 to 5 stars.