The Azden SMX-30 is a unique Video microphone as it physically has two microphones built into one body. There is a directional shotgun microphone for focused mono sound, and a pair of microphones spaced 120 degrees apart used for a wider stereo pickup. When it comes to video microphones, you would typically carry two different microphones.
Originally I thought the dual microphones may have been just a gimmick, but the Azden SMX-30 really does sound good when used in either mode. The system also includes some features found in more expensive video microphones such as +20db Gain Booster (preamp), -10db Pad (attenuation), low pass filter, and a sturdy shock mount.
I'm not going to dive into scientific data on this mic as I personally don't feel I need to. For me personally I think it sounds darn good (comparable to other mics), build quality is great, and most of all it's features make the SMX-30 very practical.
Being able to switch between stereo and mono on the fly is incredibly handy when switching between capturing focused dialogue (i.e. interviews) or ambient sounds of the environment. That makes this a great mic to have when traveling.
With an auto power on/off setting, you never have to accidentally record video with no sound and you don't have to worry about powering your mic off before packing it away in a bag. You can get additional information over on the B&H product page (here)