Ok so, this was overall a bland campaign to play.
Most of the maps are quite empty badly disposed, and indeed very, very boxy. It's really a shame because the whole Lego concept can be perfect to fit in the L4D2 game.
Also, most of the textures felt quite linear and repetitive, also the whole campaign lacks proper triggers or special effects. I think most of the Minecraft topic campaigns are quite better than this one.
I hope they rethink the whole concept and the developers offer a second lego campaign, less boxy and less linear.