The processor contains 96kB of static RAM, 512kB of flash, and a DMA controller, should you choose to do memory intensive operations. There are four serial ports, two TWI ports, SPI, two real DAC outputs, and a CAN controller. The CAN controller is not supported by any Arduino libraries yet. This is an Arduino you can use for computationally intensive tasks - not just for I/O.
Speaking of I/O...The voltage is 3.3V only! Only 3.3V and auto-switching shields are compatible with the Due. If you have any native AVR code in your sketch, it won't work - the microcontroller on the Due contains an ARM processor and is not source code compatible.
|Test Current Draw|
At 84MHz it is the fastest of the pure Arduinos. The Intel Galileo and Yun are faster, but they aren't really running Arduino code at anywhere near that speed.