Micromax is making certain amount of mobile and tablets in India since a long time. They got scucced in their mobile range but their tablet range is not good as their mobile.
Performance: -
Tab P666 have 1.2 Ghz dual core Intel Atom processer with 1 GB RAM which give very fast speed in small multitasking but if we play game and perform heavy task it will get slow. It will trouble you a lot.
Display: -
It has 8.0 inch IPS LCD display. Its display is dull whith compare to other device in this price range. It has also not HD display so you will not satisfied with display quality of this tablet.
Camera: -
The rear camera is 5 MP and front camera is 2MP. The picture quality of the rare as well as front is so low you will very unhappy with the camera. And it also not have LED flash.
Battery: -
Batter is a 4400 MAh Li-ion which not work more then one day the battery backup is very dull .
The over all performance and quality is not good so, I suggest you to look other device and try to avoid it.