It records in Wave, the sound is good. The micro is tiny, virtually invisible.
The microphone has a very good sensitivity but I recommend placing it on a table equal distance between the interlocutors, especially if you hear your voice. It's easy to hear other voices pushing but they will not be the same volume.
Whatever use you need, it's a great value.
Still, the plastic is low-end but on the other hand it does not seem suspect if you use it as "micro spy". Even recording light is discreet enough. We should be attentive enough to guess that this is more than a USB key ...