Gtechniq is as good as it comes in my book for ceramic coating, and the stuff works. I have to side with akirby here though and agree it lasts less than 12 months, and the maintenance is reapplying sealant essentially to keep it from wearing off completely. Each year it will degrade more and more until there isn't any left (the end of term) and the maintenance periods are to slow that degrading.
Ceramic coating is also far cheaper than alternatives. I did a front to back, full body coverage Suntek PPF on my Audi RS5. The stuff is amazing, it protects way more than ceramic, doesn't shine quite as much, and is self healing. The two downsides to this are cost and cost. Obviously the film is expensive, but you have to spend quite a bit on a good installer so they wrap the edges for the seamless look.
Re: windshield noise -- nothing in mine. Sounds like it has a gap in the adhesive and/or seal which is causing it. The volume should theoretically increase on windy days or as speed increases. I've always had this happen on every replacement windshield at some point regardless of the glass or the installer.