The assembly instructions are among the most detailed in the net, including an archive with pre-configured Sprinter firmware (just in case you prefer the plug-and-play approach). It uses an "ideal" direct extruder, but as the X-carrier part is standard, you can use any horizontal extruder. Smooth rods for X and Y axes are same Prusa i2 uses, while Z-axe has 50cm rods - this is the only (relatively) expensive part you can not get from i2.
Frame is 10 cm wider than i2's, which makes it solid: the more rigid frame is, especially when printing at 30cm, the less imprecise the print is, as we need to eliminate wiping motions caused by the extruder moving forward and back.
Reprap Pyramid provides detailed assembly instructions on its home page (select Assembly - Reprap Pyramid to skip intros): Reprap Pyramid