Its ease of use, ability to customize it for your specific needs, support from its development team when you do need help with something that doesn't come out-of -the box! The tool does not have as many customization options compared some other tools we've used but they are working towards adding these features so I'm sure this will be improved over time.
If price were no object then there would probably only one competitor (as far at my workplace goes). We're solving our problems related to tracking field personnel's hours spent doing various projects during their shift/day offs etc., which has been very helpful since overtime pay can add up quickly if left unchecked.