First of all, if I had to give it a rating of 4.5/5, I would have given it that. But 4 didn't seem fair to me, so 5 is the only way.
As for the product, it is a screen protector. Not glass. It protects very well against scratches from keys if you have them together with your phone in the same pocket. It also does a good job with raindrops. If the screen is wet, the touch doesn't seem to be affected, so it's fine.
Regarding how easy it was to apply.
The screen protector came without a box or anything else from the store, just accompanied by the receipt. Because it already looked like a factory packaging, I think that's how it generally comes and it wasn't a mistake. It didn't come with instructions on how to apply it and the truth is that at some point I got stuck with half of the protector applied and the other half lost. The good thing is that the first time I applied it, it was crooked on half of the screen, but when I removed it and applied it again for the second time, the adhesive had no issues and it went on perfectly. Now, if I need to do it a third or fourth time, I don't know how well it will hold. Overall, the process took less than 5 minutes and with a little imagination and assumptions, with the help of a credit card, it went on perfectly.
Finally, after 48 hours, there have been a couple of times where I pressed somewhere on the screen and it didn't respond, but I don't think it was the fault of the protector.
I recommend it, but with one observation. For the 6+€ that I bought it for, you can find much cheaper ones that possibly do the same job. So I don't know if it's worth the money.