Remarkable power in a portable form-factor. Allows effortless flexibility in testing. Their customer service is dedicated and easy to reach with zero delay (I'm talking about real-time assistance!) when those rare issues arise.
Advantages: Easy to use with an intuitive interface, effortless portability, reasonable (and elective) service fees. Short (and shallow) learning curve.
Disadvantages: Haven't seen one yet, after almost 3 years of regular use