This is the first laptop ever to have a high pixel density retina display, and is the highest resolution display ever seen on a laptop, at 2880 x 1800 pixels.
Apple has also left ATI and moved back to NVidia for its discreet graphics chip with the Keplar based GeForce GT 650M with 1GB of GDDR5 memory. This alongside the Intel HD 4000 graphics that are built into the Ivy Bridge processor, gives the laptop two very capable GPUs. In order to conserve battery the laptop will automatically switch between the GPUs as needed to provide performance and power saving as needed.
Check out the full specs here.
Apple managed to lose over a full pound of weight from the previous 15.4″ iteration of the MacBook Pro, along with almost a 1/4″ of thickness, bringing it very close to the thickness of the MacBook Air. Unfortunately, in order to achieve this they also had to remove some features like the optical drive, the Ethernet port, and the audio in port. Depending on your use scenarios some of these losses may not be a big deal to most. I will miss the Ethernet port, but there is a $29 Thunderbolt to Ethernet adapter that I guess I can live with.