I'm puzzled by the critics as well. It's thinner, lighter and faster. It has a better camera, a better display, a better cable, better speakers, better mics and better software. What's not to like?
When you're using the patent system to beat up your competitors in court over your right to innovate and crowing in public about the deep creative values at the heart of your company you need to bring your A game when it comes time to launch your new flagship product.
Not a better camera - it uses exactly the same camera as the 4S. You get panorama mode, though.
A better cable, that has essentially obsoleted millions of peripherals. "Use the adapter", not so much - I for one have an in-dash GPS / deck with Pandora and the like that I can't use with the iPhone, even with the adapter, because it doesn't support iPod out. Thanks, Apple.