1. The menu bar at the top is now wasted space. 2. The task bar is on the side.
Shortcuts to spreadsheet, worth authoring, etc, should be hidden away in the menu. Honestly how many new spreadsheets do you create every day? Not many. What you might do is double-click on a spreadsheet and have it open, but that doesn't require a big shiny shortcut being in the taskbar.
These are just defaults and can be changed, but still, I feel as if they are poorly considered defaults.