No good with Lightning Rated 1 out of 5 stars
Completely strips the grid from the calendar making it very difficult to read. You will also lose your quick open icons in the tab bar.
Apart from that, tabs are difficult to see. I can't even tell which is the active tab.
"Mostly Crystal" theme is similar in feel (though the icons aren't quite as "retro") and just plain works better IMHO. There are reasons after all, that designers have changed the way things look over the years...