Very easy to do and the guides are spot on. Took me about 20 minutes to do and no hairy moments at all.
I recommend using an ice cube tray, and put the screws from each step in a different compartment as you go along. Not that there are that many screws but it makes life easy.
'Hardest' step for me was reconnecting the fan power plug, is quite small and I kept trying to put in on upside down..not so easy if you have big fingers.