The original/old Amiga etc version had mechanical switches. They are akin to relay switches - two metal blades that you push together. My wife has been giving one plenty of stick (arf!) for about 11 years on Galaga - and I only recently had to strip & clean it.
The current version - the ones you link to - have microswitches fitted.
These are supposed to be reliable, but if you are the type who gives their joystick a right bashing, you might like to think about getting some spare microswitches (they are easy enough to swap).
Incidentally, it's quite easy to mod a USB version and put an Amiga/Atari etc lead on it instead.
Oh yeah - the new version also makes a helluva racket with the loud clicking - especially the fire button, if you have no autofire.