The Office 365 Web Apps is under constant improvement to give you new and improved features and align the experience as much as possible to the rich client.
Some of the new improvements that you can start using right now are:
Co-authoring in Office Web Apps
Find and replace edit added into Word App
Excel App now has drag and drop feature
PowerPoint has a new picture cropping functionality
Changing of file names in all of the Office Web App programs
The co-authoring is a really great feature where you can see in live time who and what changes are being made to the same document to ensure that you are not editing the same thing.
For more info take a look at: