fairly easy, unless you have powersteering.
It's just a case of undo all the bolts, and the driveshafts, then once they are out, you need to twist and lift the box to get it out, although with PAS all the pipes tend to get in the way and make it a bastard to do, when i did mine i was standing there with a gearbox on my shoulder for half an hour whilst my mate made a path for us to get it out.