Cost Effective Improvement
My aging early-2011 MBP had been slowly dying over the last couple years. I was getting close to capacity on the HDD, and the RAM was always overworked (I could see it being fully taxed in Activity Monitor). Among other things, I would often have lag while watching videos and playing flash games. Also, I had a lot of lag simply starting up and quitting applications.
Unbelievably smooth. It's literally just three steps in my opinion: get the screws off the bottom case and remove the bottom case, disconnect the battery, and then pop out the RAM sticks. You then follow the instructions in reverse order, as listed.
This is probably the single best upgrade owners of aging MBPs can do. I recommend opting for the 8GB combination, because your system wouldn't really benefit from 16GB and the increased cost of those 8GB chips. At the end of the day, we're still running older processors, and it's not like we're doing hardcore gaming (I assume) on these computers. I'm doing fantastic with 8GB, and Activity Monitor shows that I'm usually using between 4GB and 5GB while running a few applications in the background.