They work fine but they all have one weakness.
They have a tendency to break a locking tab even with careful handling.
If you tape the fragile points, this will minimize this from happening.
There are actually two locations where this can happen.
One near the headphone clip and the other just behind the middle led.
These are rotating pivot points.
see this:
http://forum.naturalpoint.com/forum/ubbthreads.php?ubb=postlist&Board=49&page=1
I will post a picture later.