I would not be to surprised. Even if there are a lot of complaints, it is still a minority with problems.
What makes you think "it is still a minority with problems"?
I don't know how many people have the problem out there,
but at least, not only this forum but also dslreports.com forum
http://www.dslreports.com/forum/r22333492-Shareport-problem-on-DIR655
many people have the same problem.
In addition, my friend who actually recommended dir-655 to me has the same issue
after upgrading the firmware to 1.31.
-- shareport working for some period time(maybe a few seconds, at most, 2 weeks),
then stops working, only rebooting the router fixes it for a while --
Based on those FACTs, I believe it is NOT a minority issue.