Adderal and Ritalin just give you a boost of energy (like a couple shots of espresso) and causes you to focus on things better. If that is studying, you find yourself studying for an hour or two without realizing it or taking a break. Unfortunately it also leads to you focusing on things like reorganizing your photograph folder or CD's. Usually you take a pill for studying, and crush and snort a pill if you want a pick me up for partying.
Negative side effects usually were similar to that of too much caffeine added with it being a real rough drug for your kidneys (don't take if you are prone to kidney stones.)
I never noticed any memory enhancement. Though I suppose when you give things your full attention as you do under the drug, you can't help but remember them better than things you aren't giving your full attention to.