Given that a large portion of what he did was turn the children's stories into epic battle sequences, I'm not sure that those elements "jive" with the gritty action as "were turned into gritty action". Every instance where the party fled or used intelligence to escape overwhelming odds, Jackson simply turned them into superheroes who blasted their way out.
A particularly pungent example would be the escape from the wood elves' fortress; in the book, this was when Bilbo finally became a fully trusted, contributing member of the group as he used stealth to sneak the dwarves out in barrels. In the film, the dwarves conduct a battle from barrels they ride like boats. The central lesson that there is something to be learned from the meekest among us is completely overtaken by the desire to have yet another CGI battle-fest.