Amazing product. Touchscreen as responsive as ever and probably feels BETTER than it did without the screen on. No scratches, dirt or dust that I can see at all, and I've had it on for maybe a year.
Installation really is not that complicated, if you read the instructions and take your time over it it's easy enough. It recommends leaving your phone off for 24 hours after installation but I can't live without my phone that long so I just left it an hour and it's fine.