Gentle is a tool that GreenAddress has developed for ease of mind of its users: Its function is to free funds from your GreenAddress wallet without GreenAddress' intervertion.
This means that should GreenAddress disappear for any reason, including out of their control, your funds are still available to you. See FAQ
The system will automatically provide you with the funds private keys and transactions to send via any service such as Bitcoin-qt, Electrum or Blockr.io
User is also able to check transactions details, export data in CSV format or directly push transactions via third-party services.
Firefox only at the moment but an app is in the works.