No open world in the VITA release. The adventure is divided into several sequences must first be completed in mode called "adventure". In this mode, the playable characters are taxed (initially this is Batman and Robin that current level can access various outfits according to needs: holding magnet to climb the wall, electric strength, etc. ...) then add Batman and others in the last levels.
In each level (as in all the Lego games) are hidden treasures to collect that especially allow unlock playable characters in free mode or bonus (the famous red bricks).
The free mode is composed of the same levels as the story but here you can alternatively use several different characters (those that have already been released). It was therefore a "team" of superhero and villains and the use of different characters can unlock the treasures that were not available with the imposed story mode characters (use Green Lantern to use the green objects, Poison Ivy to exclude plants, Lex Luthor ...).
The principle is consistent with all other Lego games.
Besides the free patterns and history, there is a vigilante fashion league only unlocked after finishing the story mode. This is only fight sequences. In summary: selecting the "arena" from the 5 available (which correspond to the sets of story mode) and you have to defeat the waves of enemies with characters who imposed succeed. As for me, it is not very interesting (we fight by pressing either the round or on the square, that's all) except to unlock new characters and for platinum for those motivated ...
Personally, I find the game easy enough and easier than the Lego games I've played on PS3. The levels also seem shorter than on PS3 and provided less detail (I did find levels of Lego Batman 2 less empty than those of Lego Harry Potter Vita). The game graphics are fine but the cutscenes are very very ugly, as was already the case for Lego Harry Potter on VITA. Adding voice in cinematics (a first for the Lego games) is pleasant against (making it even more of a pity that the cinematic graphics are very ugly).
For the gameplay, nothing to report, it's classic Lego: we run, we break, we cling, we fight, it activates mechanisms .... all this is done without playability problems.
Level term life story mode ends fairly quickly and without difficulty / brainer for an adult player (for those who did not know, the difficulty level is not adjustable in the Lego games). The duration is extended by having to redo levels in free play with good characters to unlock all the treasures.
I put 3 stars because of the poor quality cinematics (even if it's a detail, it shows a lack of finishing the title) and the classic side and without innovation of the game (especially when you have already played to other Lego titles). Maybe for casual or younger player, he deserves 4 stars.