The GreenAddress wallet is a Bitcoin only HD wallet with security as its main focus. It is primarily used as a desktop wallet, but only through a Chrome extension. That was done by design to provide additional security. There are also mobile versions available for both iOS and Android operation systems.
Multi-signature is available to add security, and there are four different types of 2-factor authentication available, and there are additional features that have been developed to appeal to experienced Bitcoiners. Those new to Bitcoin might find the wallet a bit overwhelming, and a simpler Bitcoin wallet might be a better choice for your very first wallet.