Thanks - it looks like a really good introduction to PIC hardware.
It is showing its age a bit in the emphasis on instruction sets and assembly language, and in the chip they have chosen to concentrate on.
The PIC16F887 which is referred to as "one of the latest products from Microchip" is at least five years old now, and the PIC18 range and even "16-bit monsters" such as the PIC24 chips offer a cleaner architecture, more features and more memory at what is often a cheaper price these days - and make it easier to use a high level language such as C.