No personal experience of Asus notebooks, but their motherboards are in 25% of the world's PCs. As an ODM/OEM, it makes or has made notebooks for Apple, IBM, Sony, Sharp and Samsung. About 40% of its production is ODM/OEM.
The Ensemble line in North America has a 2-year international warranty on parts and labour, with an option to extend it to a third years, US only. In other countries it's 2 years international, with the option to add a third year international. There's also a 30-day zero dead pixel warranty.