Zsh is a much better bash.
It is a command line shell that will improve your productivity. For example, it can autocomplete common commands. If you type git a, it will prompt add, am, etc.. And it has community driven theme.
Install ZSH
sudo apt-get install zsh
To get started, go to oh-my-zsh on github.
Try using the chsh command.
e.g.
chsh -s /bin/zsh
You can confirm the location of zsh by running whereis zsh, or alternatively simply run
chsh -s $(which zsh)
If you want to change the shell for a user account other than the one you're logged into, you'll need to run it as root, so to change john's shell, do:
sudo chsh -s $(which zsh) john