The Covert Cam is built to look like an infrared sensor of the type used by burglar alarms. The camera itself is hidden behind a small black hole in the plastic case.
It produced good pictures in the daytime. Colours were realistic and the amount of detail captured was slightly better than the more expensive VIS349. It has a microphone, too. Anyone speaking at a normal volume near the camera could just about be heard.
Short cables extend less than 20cm from the rear of the camera, so you'll need an extension cable to connect it up. With no infrared LEDs, it's no good at night time.
The Covert Camera is a little expensive and you'll need to add both a power supply and an extension cable. It does produce a good picture, though. The BulletCam is better value, but this could be ideal if you want a hidden camera.