Wanted to upgrade both the memory and storage from 8GB RAM to 16GB and from 750GB HD to 1TB SSHD hybrid drive respectively.
Piece of cake! iFixit's repair guide for the 2011 MacBook Po took all the fear out of opening up the case and and the process of removing and replacing the two components. iFixit's Spudger was made for the job of gently removing the battery connection, and it will be useful again when I replace the battery.
Take your time, have a good work space with lots of light. I suggest using the non-slip rubbery drawer liner material for a work mat to place the MBP on upside down. Have a suitable container to put the little screws in before you start—an old plastic ice tray works well. Have an iPad or other computer set up nearby to view the iFixit instructions or print them out ahead of time. Really, this procedure you can almost do by just memorizing the steps, it's that easy (unlike older MBPs). One last little point to remember is to re-connect the battery before replacing the back cover. It's easy to forget, don't ask me how I know.