The main problem we solved was to automate our internal workflow process, allowing us in one click send an email or make phone call from within Salesforce! We are using it since almost 2 years now and there is nothing that I dislike so far.
There are some minor issues with this platform (sometimes you have problems sending emails) but overall everything works as expected. If your looking for a tool to solve business needs then go ahead otherwise keep searching - maybe someone else will find something better? Automate all sales activities at work-flow level by building automated outbound campaigns;.