If you have a lot of files and need something to help you search through them quickly and easily, ACT! is a decent choice. It has a variety of functions on top of organizing contacts and clients. Task managing, scheduling, reports, grouping, and a variety of other things.
However, the UI is a little un-intuitive and visibly outdated.
Additionally, support for ACT! is a little slow. It often requires a phone call and lengthy back and forth.
Overall, the software does its job well, so long as the user is able to overcome the learning curve required to efficiently utilize it. Review collected by and hosted on G2.com.