Assembly is straightforward but takes a while. Comes with all the tools you need. Everything is metric. I recommend labeling the screw packets before starting so you know which size is which.
I ended up tightening the drive belts after initial assembly, which is tough to do. I used vise grips to help. Do not overtighten the belts however, because it can cause strain on the servo motors.
I also added a couple washers (of my own) to the pen mechanism to reduce slop. On either side of the arm that raises / lowers the pen. If you do not add your own washers, you can also use the white plastic spacers that come with the plotter.
Ensure that the pivot screw that holds the drawing arm to the upper assembly is tight however. Horizontal slop will lead to impersice drawings.