The "usefulness" of an expansion is entirely subjective I think. You have to take a broader view of the cards included in the expansion AFTER it has been added to the main deck and even then after a number of plays.
The object of every expansion is not necessarily to make the game harder, like you might expect in a campaign from an RPG or a video game for instance, but to add a bit of narrative or substance to the game. Novel twists are added, like optional rules, or alternative endings and <insert cool idea here>.
The game (story) of Talisman relies on the deck of cards (pages of its book) which changes from game to game. You can travel around the countryside and not meet anything of note, except a lost Princess and a Wild Boar. However, the same journey on another day might have you facing a Giant, three Dragons and the Devil.
As The_Warlock rightly says, the difficulty of a card is determined by when it is encountered. We have all been surprised by the weakest of enemies once in a while.
When expansions are released there will of course be cards that people might feel are disappointing or "weak". I myself would like to see a few "Über Enemies" but I am sure I wouldn't want to draw 3 or 4 of them in a row as that would spoil the game.
We all know there are "X amount" of expansions to come given the trend with FFG releases, and who knows what else besides. I am confident that enemy attributes and card numbers will all balance out in the end. Until then, I am prepared to enjoy the narrative that each game offers.



But V. can do that too so take no offense; he can be pretty astute too, and I don't think he's intending anything by sticking too his guns.




