Prototype
I built a prototype of the board to make sure the hardware works. The board was etched using the laserjet-fuse-transfer-principle, and just one-sided.
The board actually is quite easy to build: The DIP-parts are a piece of cake, if you drill the holes for it in the right place, the display is click-on, and the TQFP-chip isn't that difficult to solder if you know how: First of all, align the chip and solder a few corner pins, so the chip is fixed in place. Then, apply a lot of solder on each side of the chip, so all pins on a side are covered in one big blob of solder. Finally, use soder wick to remove the excess solder. Co/adhesion will almost guarantee that the pins you wanted soldered in the first place, keep a bit of solder under them.