The dongle actually goes together pretty easily.
The most common mistakes are...
1. not aligning the dot on the XTAL oscillator to the dot on the PCB.
2. putting in the mosfet transistor in backwards
3. not using a programmed PIC - these do not come pre-programmed
4. putting in other chips backwards.
5. bad solder joints
If you watch out for these mistakes, you should be fine.
One other thing to watch out for, but you won't know until you test your dongle, is a bad usb module. This is not common, but has happened a few times. This will usually manifest as windows not detecting the dongle when plugged in.