sides...
side effects i personally have experienced:
just a little background - i used ecstasy for on and off for 4 1/2 years. never took it more than 2 days in one week. at the heaviest stage i would take 2 - 2 1/2 pills in one night, once a week. this was for about 4 months. compared to many people that i know, my use was low to average. combined it with shrooms twice, but never combined it with any other drug except for pot a few times. don't/didn't use any other drugs or alchohol during this time period.
sides:
loss of short term memory (wonder if i will ever get it back), drawing a blank when asked a question that requires thought, forgetting simple words that i should remember (like it's on the tip of my tongue, but i can't remember it), depression, severe social withdrawl.
and i'm not some dumb ass either. i've always been (or always was) a very intelligent person who excelled in school and academics. i was a very socially outgoing person, but since my use i'd rather avoid people than be social.
i'm not trying to scare you out of trying it in anyway...just giving you a personal account of the downsides i have experienced. everyone is different and i know people who have used much more than me and seem fine.