I've performed this procedure numerous times. While it's not particularly difficult, it requires patience - a LOT of patience. Dozens of the world's smallest Philips-head screws. The iFixit guide helps tremendously.

What strikes me as nostalgic is how repairable these machines were. No proprietary screws, the HDD used a standard (at the time) form factor and interface. The batteries could even be torn down and rebuilt as they used standard cylindrical cells inside. Hell, the keyboard could be replaced without opening the cover! The only thing that was proprietary was the Airport card - which was under the keyboard along with the SODIMM slot, and both could likewise be replaced without opening the laptop. Those days are long gone.

One item of note is I suspect the older versions of OS X lack SSD TRIM support.