There is nothing worse than investing time and money in someone else's project only to find there are flaws in the design. In the interest of full disclosure for a prospective builder, here are the issues I am aware of :
1. The power switch doesn't really protrude from the case. I manage with the side of my nail, or you could use a cocktail stick / match etc.
2. The screen is 1 mm off central when in the portrait aspect. You might not have noticed... you will now.
3. The sound is quiet. It's a tiny speaker with no amp, so it isn't much of a surprise. It is what it is :)
Problems that might come up:
1. It wont turn on.
- Have you checked there is a programmed and working game cartridge inserted? It wont come on without one. Also check the battery is installed correctly. Positive down. Then start thinking about looking at your soldering.
2. The joystick falls off.
- It wont really hold on there without a small amount of superglue, however only do this after you are 100% sure you no longer want to take the case apart.
3. The screen case and joystick case are misaligned
- We did test the case designs on a couple of printers and with different materials, and are satisfied it will go together without issue. Slight variations could be caused by a badly aligned 3d print bed, but another cause could be that your joysticks female connecting pin is not level. You could risk just bending it a fraction.