While Amazon Web Services does a great job developing a nice and easy to use GUI console for its suite of cloud services, nothing quite beats a great command line client for scripting.
A major upgrade, when compared to the old client, is that this client is capable of outputting responses in user-specified formats. For instance, you can output as JSON to pipe to a JSON parsing utility, or the output can be displayed in a color-coded organized table format for quick human consumption.
The CLI client also supports the notion of profiles that a user can toggle on and off with a profile flag. This is a very useful feature for any AWS users who have to manage multiple access/secret keys for multiple groups.