Their customer service is outstanding! I have never had an issue with any of my calls or emails for support resolved quickly by their team members who are always friendly and knowledgeable about all aspects of our systems.
They also do great work when it comes time for implementation - they understand how we operate as well as what works best for us so there's no guesswork involved at that stage which makes things go much smoother. We've been using this product since 2015 but only just now got around to reviewing its features/capabilities compared to other products out there (such as Google Apps). It does everything you need from email to calendar management including file sharing capabilities within your organization via SharePoint Online.