A few things to note:
This first gen device will likely be a duel core, not quad. Quad core CPUs will not be supported by WP8 until GDR3 is released this fall/winter, so unless this is just a product announcement for a phone coming out later in the year, then it cannot be a quad core device.
"Indeed please explain, because I see something that doesn't function at all at low light."
It does just fine in low light. It uses a huge sensor and supersampeling to compensate for low light situations, but where most cameras loose quality with the supersampeling this can still pump out a full 8MP image. Check out the Pureview 808 for an idea of what it can do. This will have had 2 more years to mature the tech, so I am pretty sure it will be pretty sweet.
It is still not going to replace a DSLR or anything, but it is going to put camera phones and little point and shoot devices to shame, and hopefully give the WP platform some better legs to stand on.