I got this game for my 3DS XL after playing the demo of Lego Batman 2- Promptly returned it!
One of the things I'd loved about the demo was the voice overs for all the characters- I didn't realize that Lego Batman 2 is the first game that the Lego figures speak in! Without audio, the story of Lego Batman is told through comic book-esque picture panels with semi dramatic music in the background. They look good but are rather boring to watch, and are not skippable or speed-up-able, at least the first time through.
Once I got into the main of the game I was assaulted by the graphics. The game being 4 years old now, and my having a 3DS XL, makes for some seriously grainy graphics. Nothing is particularly clear and it looked terrible.
Otherwise, the game IS enjoyable. The puzzles are fun to figure out, switching out the various hero costumes adds a lot of possibilities to the game, and the controls feel nice and tight. But the lack of voice acting for the characters and grainy, blurry graphics due to the XL's larger screen makes for a lackluster experience.
I feel this game would have been fantastic when it first came out. However, if you want a batman game on the go, or have a new 3DS (especially the 3DS XL, as the bigger screen seriously kills this game's graphics) I would not recommend it. Go pick up a copy of Lego Batman 2: DC Super Heroes instead. All in all the game play and graphics are far better than the first, and the voice overs for the characters blow the first Lego Batman out of the water.