I don't care for the leaderboards, but I still love the trials. It has different challenges for stealth, combat, and even puzzles. If I were you, I'd look at some videos of the gameplay before you decide wether or not to get it.
If you love the game, why not buy the DLC and support the developers? ..
Simple, when they release a dlc I want I buy it. If they release one I don't want then I won't touch it. Lets them know what people want and what they don't want and prevents me from wasting money on something I didn't want. Win/Win I think.
i myself do jump the gun on DLC, in the past that is, and then realized that sometimes the DLC isnt the game, if that makes sense, like this isnt really new levels or anything to the game besides a leaderboard and time trials (from what i understand)
and thats where im starting to smarten up and stop buying DLC for games, UNLESS its adding to the game in a way that increases replay value, and IMO this doesnt, to some of you it does, but like other have said this is just a chill game....