I like that it is easy to use, has many features, can be used in multiple ways (including web-based), and allows you to work with other databases as well as SQL Server.
It's not free but there are options available for those who need more than what is included in their standard license. We have been able to connect our database of customers across all departments within the organization. This helps us keep track of billing issues, customer service requests, etc., which previously was difficult if we had to rely solely on spreadsheets or emailing each department.