The Block can be configured to show contact methods including: Email, Message, and Phone number, the user Profile picture and online status - similar to Skype, Facebook Messenger, etc.

Due to the fact that the Block displays personal information from Profiles (email and phone number in particular) it should not be used in Courses that allow Guest access for obvious privacy reasons. The developers make this clear - good

It might be possible to replicate/access the functionality of this Block in others ways within Moodle, but the effectiveness of the Block is that it gathers information and communication methods into one location - so where appropriate, perhaps in courses with high interaction, it will be very useful indeed.

You can try this Block yourself for real on our public plugins site: http://plugins.moodlebites.com

The Block is extremely easy for Students to use - requiring nothing more than a 'point and click' approach.

It's good that the Teachers are listed above Students in the Block.

If used, the Phone number is displayed from the Phone field of the user Profile.  I'm nit sure is the Mobile phone number would be a better choice?  In a perfect world the plugin should probably give the Moodle administrator to choose which of these could be displayed, or both perhaps ?

In my testing, using the Clean Theme in Moodle, the Block does have some display elements that appear slightly odd.  The font / heading used seems very large, and the icons for the Email, Message, and Phone don't really hang together well with the core Theme icons.  This results in the Block looking somewhat 'out of place' within the wider styling of the Course and other Blocks..  These are relatively small issues and don't affect the functionality, but a little more work in these areas would results in a more integrated and slick appearance.

I have not reviewed the coding style and readability of this plugin.  However, there are some very experienced developers maintaining this plugin, which have contributed and maintain several other well respected Moodle plugins - so we can expect the standard to be very high here

Development of this Block originally started back in 2011, so it has 'stood the test of time' in terms being updated regularly to continue working with new releases of Moodle.

I haven't noticed any performance issues when using this Block, although in a Course with a lot of users it could slow down page rendering.