Wow! Apple sold 5 million iPhone 5s in the first 3 days. There should be good deals on used iPhone 4 and 4S models in the coming weeks.
The iPhone 5 has a new microprocessor and double the memory of the iPhone 4S. The iPhone 5 is almost twice as fast as the 4S when running benchmark tests (both phones running iOS6). The iPhone 5 is also somewhat faster than the current iPad.
Benchmarks show the iPhone 5 is running neck-and-neck with the fastest Android phones on the market today, with Android winning some benchmarks, Apple winning others.
here's one web page reporting benchmark results
http://www.pcmag.com/article2/0,2817,2410034,00.asp
iPhone 5 owners are reporting one cosmetic issue. The aluminum back scratches easily. If you plan to carry your phone in a pocket with your car keys, better get a case for the phone. Or cover the phone front and back with a clear plastic film like a screen protector. Zagg is one company that makes the plastic film.