As compared to the web interface, the main advantages are:
* Workflow -- the interface is designed to support a workflow similar to reading network news or mail. In particular, it is designed to deal with a large number of review requests across a large number of projects.
* Offline Use -- Gertty syncs information about changes in subscribed projects to a local database and local git repos. All review operations are performed against that database and then synced back to Gerrit.
* Speed -- user actions modify locally cached content and need not wait for server interaction.
* Convenience -- because Gertty downloads all changes to local git repos, a single command instructs it to checkout a change into that repo for detailed examination or testing of larger changes.