This extension has potential to be great, but is lacking in some major areas such as actual support for the product, a knowledge base or support forum, Joomla links to supposed forum (broken links), a mini-calendar that does not display multi-day events, a main calendar that does not display the current month or actually allow you to press Next to get to the next month (unclickable) and when you do actually contact support through their reseller's 'contact us' option, they did respond to the initial message stating they will get back to you... so at least someone or a script is responding to the contact us page, but there is no way of knowing if they will ever get back to you as they already have your money. Perhaps they are working on the issue already, but without a public forum or common questions and current bug list to show you they are aware of the issue.. it's disturbing that there is nothing you can do for a broken product except wait. Meanwhile I am researching the other related products.
So, you pay for what you get. The price is right and honestly the rest of the product so far functions correctly and is easy to setup. They also have pretty decent documentation... but if it's support or a working calendar function you are also needing for your manager, then purchase at your own risk.
Giving it an 'average' ranking because the actual event setup and process works and the price is right. I would pay twice as much for a working event calendar though!