Easy But Lots of Screws!
Replaced Left I/O Board. The previous board's MagSafe connector had scorch marks on it.
It went fairly well except I have no sound! I probably just didn't get some of the connectors seated probably which I will check out in the next few days. However, I did wind up with an a dark gray wire with a black connector that I wasn't sure where it plugged in to. It was running with the AirPort Extreme wires. There was no mention of it in the instructions nor could I find any information on it on-line. Other than that, the replacement instructions were excellent and very accurate.
Just make sure everything is seated properly before you put the case screws back in!