My fan was getting very loud, so I blasted it with compressed air...which caused it to die. After this, my MacBook overheated constantly.
Things went without a hitch......mostly. The middle screw between the ram bays had a stripped head, so I had to drill it out. Other than that, everything in my computer matched up with the guide and worked well!
Always apply plenty of pressure when unscrewing the screws in the battery bay. Since you can't attack them straight on, you need to be sure that you aren't stripping the heads.