The first two Batman games were pretty great, especially the first one since it did a whole lot of firsts including probably best superhero game, best personification of Batman in a game, had some great voice-acting and a fresh and well-made melee combat system and a rather great atmosphere and pacing that never made it get dull.
Also great work with the modeling/animation/level design. And all of that from a rather unknown studio and without any expectations for greatness (and it was definitely a breath of fresh air after relative disappointments like Mass Effect, GTA IV, Bioshock or Fallout 3 at that time).
Only a few of the boss fights were largely disappointing. Henchmen variety, the difficulty and AI could've been improved (for instance I remember how enemies apparently didn't notice their colleagues being taken out a few steps away:
http://i.imgur.com/fdWhVym.jpg ) and I didn't really get why the main plot was wrapped around the whole "Titan" thing, it seemed kind of stupid and a missed opportunity to tell somewhat more of a psychological thriller tale around Joker similar to the one with Scarecrow but using a different angle.
The second game was largely more of the same and somewhat less focused than the first but still good and fun. They improved on some stuff, but made other stuff worse.
I'm gonna wait and see with this one and probably get it when it's somewhat cheaper.
I agree though that it would be great if they could add some more detective-ing and sneaking around the city (like in Batman: TAS) as fresh gameplay elements and maybe solving some more "banal" problems between shit going down to change the pacing up a bit (playing as Bruce Wayne for a few sections at Wayne Enterprises or some events might not be too bad either). It made sense to mostly be fighting in Arkham Asylum, since it was full of insane lunatics trying to kill everyone. It made somewhat sense in Arkham City under the context of the story they had written although it was pushing it, but if even Gotham City in its entirety is overrun by random mooks who you've constantly got to fight and not much else they're kind of jumping the shark a bit like that last Batman movie.