I feel this game catches way too much flack when it is actually a GREAT game. It has its ups and downs but if it were the only entry in the Arkham series, people would think of it a hell of a lot differently. The past games set people's expectations higher than heaven. Disappointment is to be expected with unrealistic expectations.
The game is beautiful. It adds a major gameplay feature; the Batmobile. Too Batmobile heavy? It's debatable but why can't that feature be as important as the other core mechanics like a classic brawl or stealth encounters? The only thing I could ask for is more beautiful interiors that's you didn't have to drive through like the Asslyum or Hugo Strange's Wonder Tower base for example.
This is the best game in the franchise. It tops each Arkham game in terms of content, graphics and gameplay. You get way more of everything but somehow people are missing that.
Not a fan of how games/dlc are done these days but Arkham Knight's $40 season pass stuffs the game very full by this point.. and there's more on the way. You get the skin and Batmobile from each film/TV rendition next to vast selection of different suits from Batman comics. The Arkham episodes were hit or miss depending on its content but these mini chapters let you play as other major Batman characters. The game is hefty at this point. This game really goes out in a bang in all areas.
Arkham Asslyum and City's stories are still some of the greatest Batman stories written by veteran Batman writers. Arkham Knight didn't have the same advtange but manages well. I found it a great final chapter to an already phenomenal Batman story. It draws inspiration taking bits from The Dark Knight Returns, KnightFall, The Long Halloween and, the film, The Dark Knight Rises. It's delicious.
One thing that disapointed people with the story is the rogue gallery isn't stuffed in to the story like City or Origins. Instead its more refined like Arkham Asslyum but you still have the rest running around Gotham in side missions. So, you really can't complain.
I think why more people don't appreciate this game is the same reason GTAV disappointed me. When there's an excessive amount of hype, you start to envision a game that's made by god. Arkham Knight isn't made by god, unfortunately, but it is the ultimate Batman experience to date.