Further to my comment here, I discovered that LBP removes some of the new(?) classes WP 3.5 uses for galleries.
This was what caused my styling to go out of the window (because styling was based on these removed classes).
In particular, I had used the gallery-columns-[n] class (fits nicely with a grid).
Here's an example of the gallery classes without LBP:
gallery galleryid-6 gallery-columns-6 gallery-size-thumbnail
And with LBP enabled/use for WP gallery checked: