Arrhh!!! Just can't solve this Sudoku

To be honest of late I have been getting a little bored of Sudoko, and that could be why I'm having difficulty solving puzzles that I think I should be able to solve relatively quickly and easily. Either way this sudoku puzzle is the one I can't quite get my head round. Any advice would be greatly appreciated.

Hillside Sudoku

A year or so ago the Sun newspaper created the largest Sudoku puzzle ever, by painting a huge puzzle into a hillside. However it turned it was not a genuine Sudoku puzzle as it has more than one unique solution...