In defence of the Invisible Shield...
1) Zagg offer a 45 day no quibble money back guarantee on their website - If you don't like it, make use of this!
2) Zagg offer a lifetime replacement (you pay the postage) if you shield becomes damaged, scratched, etc. - Folks SHOULD make use of this!
I have been a long time user of IS on just about all my gadgets, and I do admit to being a bit of a fanboi. Yes, I concede that the installation is tricky, particularly the first time you do it, but any good screen protector needs to be applied with due care and attention.
I currently have a perfect installation front and back on my iPhone 5 and that's all the protection it needs. Yes, it's true, they can be susceptible to peeling corners, and the degree to which this effects you can be impacted by all sorts of things. In my experience, a shield will last a minimum of 6 months, and often up to a year. I've used plenty of "standard" screen protectors, and they can need replacement just as often if you happen to catch a corner, or scratch them with keys etc. (scratching is something which IS is pretty much immune to).
Since the IS is a wet install there is no way that the end result should include air bubbles. That is one of the primary advantages of a wet install. Performed carefully, and given 24+ hours to cure / dry, you should end up without a single blemish under the screen. Another advantage to the wet install is the opportunity to "get it right" by sliding, moving, and perfecting, which dry installs are much less forgiving with... Yes, it takes a little practice, but there are lots of very good YouTube clips with which to learn!
I'm not saying IS is for everyone. It is definitely an acquired taste, particularly due to the "orange peel" effect which many folks don't like. But, I think they should be given a fair crack due to the 2 points at the start of this post. If you don't like it, they give you your money back! You can't say fairer that that
There are lots of us Zagg fans out there, so to suggest it is a bit of a scam by shareholders is a little disingenuous IMHO, a confirmed InvisibleShield Fanboi!