i'm not going to do the 'what i learned' stuff. for many activities, in describing the tasks that i did the stuff i learned (in terms of skills and knowledge) should be apparent. to me, it seems like listing the more emotional stuff i learned (e.g. how it changed my perspective) might come off as corny.
I chose to be descriptive. Some may say I'm taking a risk because certain adcom members would rather just read the fact. Others, it's been said, appreciate a good anecdote. I'm going for the middle path--my descriptions are about 500 characters each (3-5 sentences).