It's easy to use and it has all of the features needed in one place! I like that you can run tests from a browser or directly off your network with no additional software required.
There are some things about the interface that could be improved (ease-of-use). But this is nitpicky stuff - if you're looking for an easy way to manage testing across multiple devices, then look no further than Netrounds. The ability to quickly create scripts/test plans and execute them from anywhere at any time allows me to get work done when my team needs help most.