Yes. The app works offline.
You can add content to the app without being connected to the Internet. The only functionalities that require to be online are the ones directly linked to the synchronization. You need to be connected when using:
- Community: to find people to add to your Circle of Trust
- In/out : to send or receive new information. For example, you can create a new sharing rule with an existing contact but the record shared won't be sent until you are online
- News: the news are cached so you can always access them but once you want to know more and click on a link to the website, you need the Internet.