Welcome back!
I have often found the learning curve to be quite extensive proportional to the amount of time taken away from the game. From my experiences doing just the same thing not too long ago, not much has changed. Obviously, updates to MQ and macros / plugins. But mainly, what I would encourage is re-read all the resources from the site like you are a total beginner. That's what I do, and it helps a lot.
EDIT: It all comes back relatively quickly once you start reading and playing again. Try to not get discouraged!