These games are easy to play, but I am in it for the story. You want challenging and great gameplay (but incoherent story), pick up Dark Souls.
Revelations and Brotherhood did not get bad reviews by any means, just not nearly as revolutionary as the last few games. Unless, you take the multiplayer into consideration which was very refreshing.
I think they want you to feel unstoppable, but I am hoping for a way to tweak the difficulty on the next one.
For those on the sideline about Brotherhood and Revelations, they are excellent games. No doubt about it.
Somewhat related: Dark Souls, which I mentioned above, is on sale at newegg for less than $20. Highly recommended.