I've unresponsive home button on my iPhone 4. It gave up after 3 years of use.
I spent 2 hours mostly to disassemble iPhone. The guide didn't mentioned some pitfalls.
1. Find a way to organize disassembled parts.
2. Heat up touch screen before trying to take it out (place iPhone before table lamp or any spotlight - works just fine).
3. Look for any small parts not mentioned in the guide - don't lose 'em (there's a rubbers gasket and small metal coil)