The disk tray is not very good, it has a small recessed section to hold the disk but when ejecting it can slip out of this recessed bit and slide against the tray meaning your games get scratched. My friends Q used to do it all the time like the tray was coming out too fast and suddenly stopping so it would bump the disk out, could have just been his particular Q though.

If you are buying a unmodded one then it won't be playing anything except japanese gamecube games. The us/japan thing was only if it was modded no stock Q had all region built in. Can't say the prices they go for nowdays are worth it, the style hasn't aged well nowdays it looks kind of tacky to me but thats totally a subjective thing.