SharePoint 2013 Server Enterprise and Office 365 support SharePoint apps that can be used to display data from external data sources via Business Connectivity Services. With SharePoint 2013 on-premises, you can deploy a External Content Type as a full trust farm solution, which is something that you cannot do with Office 365 Business Connectivity Services.

Using Visual Studio, you can create a OData External Content Type and then deploy it to an Office 365 SharePoint Online site as a SharePoint App.

Create an External Content Type using Visual Studio

Using Visual Studio, you can create a SharePoint hosted app, and then add to your project an External Content Type which will in turn prompt you for an OData URL. Exact instructions can be found here

Once the app is deployed to Office 365, the data will be rendered using an External List. However, with the lack of the Design View in SharePoint Designer, it becomes difficult being able to style the data. Using our Data Viewer App for Office 365, you can connect to SharePoint lists or Business Connectivity Services External Content Types, and then begin styling the data using the App’s properties.

Data Viewer App for Office 365

With the Data Viewer App for Office 365, you can group multiple columns, add conditional formatting, Use Create, Update and Delete operations, as well as sorting, data formatting, calculated columns, aggregate functions and filters.

Configure the Data Viewer App for Office 365

The Finder, Specifc Finder, Creator, Updater and Deleter methods can be set for the External Content Type and the External Content Type app selected from the treeview.

Styling and Conditional Formatting

The OData columns can be selected, Data format set along with column alias and styling.

You can download the Data Viewer App from either the SharePoint App Store or here.