I was a little confused myself as to how the riddles were in fact not exactly riddles and more finding collectables, however as far as collectable hunting goes I find what Batman offered enjoyable.
Why? Because it showed you the general area. It wasn't just lucky finds, I had no probems finding any of them within maybe a minute or so of being in that area, however don't let the riddles hamper you on your first playthrough - you can do these at the end.
The patient interviews were very nice.
The gameplay itself, indeed does lack depth but you can't deny it's pretty fun and fluid. There are a lot of games which essentially play themselves in there combat fields, Darksiders, God of War... but if you get into the combat challenges they are pretty difficult, and I felt the combat style properly represented batmans own combat style from comics/films.
The gargoyle thing, did indeed feel a little scripted, and it was a little disappointing at first however there are plenty other objects to grapple as you go through the game. I think gargoyles shouldn't really have been used throughout, but whatever.