I've just reached the end of my contract on a 4S having previously owned (and enjoyed) the 3GS & 3G prior.
I never thought I'd consider moving away from iPhone in the imminent future as I love the GUI etc.
Having read over the last few pages of this thread, however, and various recent press articles, I'm very disappointed that Apple have chosen not to make a change to better quality anodization to eradicate this problem.
We probably all expect a 5S model to be announced and shipped in the next few months, so hopefully they will make the change then and deliver a true premium product, even if it means slightly less profit.
If not, I may find myself reluctantly heading elsewhere, which would be unfortunate.