Having worked with capella 7 you will know about 100 icons on several symbol bars. These had to give way.
On the top symbol bar in capella 8 you will find only essential commands such as "Open file", "Print" and some more.
All commands needed to enter and edit notes were rearranged: Everything needed for note entry (note values, octaves etc.) are positioned above the mouse piano, more commands can be found in the Edit area to the right.
This area displays commands which are useful in the corresponding context. You will see that the Edit area displays different content depending on what you are doing: Entering or marking notes, editing a text object...
By the way: When you were used to work with menu commands, not much has changed: Most keyboard shortcuts remained unchanged.