I just had a Clearplex windshield film installed by the manufacturer at the Porsche Parade in the Poconos last month. It's too early to tell you what I think about it, as I've only driven it ~900 miles since then. But before getting it installed, I got a couple visible chips in the windshield - so I figured I'd give it a try when I saw it was being offered at Parade. The manufacturer was there doing it for $350 installed.
The film is surprisingly thin - much, much thinner than PPF in fact. It's supposed to be good for 3-4 years on the windshield, but with a pampered garaged car they said it could last much longer. You have to use window cleaner without ammonia, and they recommend waxing the windshield once a month to keep it slick and hydrophobic (I'm normally a RainX guy, but I might stick with wax and see how it goes). The worst thing for the windshield film it is a dry wiper blade pass, or dirty/gritty wiper blades, as those can leave micro scratches on the film which eventually will be visible and look bad.
I was driving home from the Poconos a couple days after getting the protection applied, and I passed a farm truck on the highway with a load of loose dirt and gravel in it's bed. As I approached and passed, my car was peppered with debris in the 5-10 seconds it took to get past him, but the windshield was damage-free after cleaning it. My car gets tracked about 3-4 times per year, so it's feels better having a little protection for when people run off-track and bring the gravel and small stones back on the track with them.