The ease of use, being able to answer calls from any device at anytime is great! It's also very user friendly when it comes to managing customers or even your own contacts in an efficient manner using their app store/app center.
So far I have had no issues with this software so far but if there were anything that could be improved upon I would say maybe more customization options such as allowing you to add custom fields etc? Not many other companies offer these kind of tools (not saying they are better than others just offering different types). Call Queueing has never been easier now we can place our agents where ever they need us to be without having to go through the hassle of physically going into each office which was previously impossible due to security reasons.