Odd. I can see signal drop only when I touch the specific seam on the side of the phone - I can cover the entire outer rim of the phone with my hands and have no problems so long as I leave the little black line clear. As a result, any way I would hold the phone with my right hand, and most of the ways I would hold the phone with my left hand are fine. For data, the issue is a bit worse - I can hold it comfortably in my left hand for data, but it's a non-instinctual way to hold it. Right hand is fine, though - I can easily avoid touching the seam.
I saw in another thread someone else that had a much more severe problem.
I suspect there are two issues. One is the problem found and demonstrated by Consumer Reports, where a noticeable drop in signal happens when a specific spot barely a millimeter wide is touched. This problem is widespread - perhaps even universal. It is also not a problem that significantly impacts normal usage of the phone.
Then there are phones with more severe defects that have device-breaking signal problems. I've seen a few people on forums mention these. Even assuming (as is always the case) that some of these people are trolling, it's clear there's a non-zero rate of this defect. Without very good data, it's impossible to tell if this problem is particularly widespread for an electronic device. After all, every piece of electronics has a non-zero lemon rate.
The former issue has gotten unusual media attention and Apple is thus going to have to fix it to avoid egg on their face, regardless of the fairness of that. They'll probably do that by making bumpers free.
The latter issue has gotten caught up in the former issue, and is being mistaken for it, but is, I would guess, within the normal parameters of device failure and solvable via normal return/repair channels.