Always hated drop down on hover menus because it just doesn’t behave nice:

• when you want the menu open, you can accidentally hover out and makes it close
• when you want the menu unopened, you can accidentally hover over it and makes it open

Today, I saw a drop UP menu. It’s kind of refreshing actually. The menu doesn’t get in your way as much. I understand the drawback is the limited space you may use until you hit the top of your viewport instead of the unlimited space you may use going down.