I like that it has an easy to use interface, as well as having access from anywhere in the world! It's also very user friendly which makes using this application quite enjoyable.
The only thing I don't love about this product are its email reports - sometimes they're difficult to read because of formatting issues or they look old fashioned (i'm looking at you outlook). This tool helped me get more leads with my sales team. As well as tracking what emails were opened and clicked through for each prospect/lead we could follow up with them later if needed instead of manually doing so via excel spreadsheet.