Great feature.....but lots of bugs...
1) Grid elements can be placed on top of others, which is certainly not intended behavior.
2) Grid leaves lots of random blank grid space.
3) Switching from 2 to 3 columns and/or back results in closed up white space (see #2) reappearing.
4) Switching from 2 to 3 columns makes the 3rd column ads. I get the need for ads but this makes the 3 column option less helpful.
Chrome (latest), Windows 7.