While I use dedicated graphics myself, I have to say that the AMD Llano and Trinity chips have impressed me greatly.
I have built systems for friends and relatives who have been on tight budgets, and the performance offered has blown me away, I am fairly certain my next laptop will contain and AMD APU unless the new Haswell GT3 beats AMD's New Richland
As for Gigabyte motherboards, they do offer incredible reliability, all brands are doing really well at the moment, my only gripe with Asus was their lack of windows 7 support at launch, especially with relatively new boards, but no-one manufacturer is completely flawless.
Enjoy building the AMD rig, do check for upcoming Richland APU's as they should offer a performance boost over the current generation.
Don't forget to back your system with a decent power supply
and have fun.