Ecstasy is MDMA, a psychedelic-amphetamine (characteristic of both a stimulant and pyschedlic). Its a wonderful drug really, so long as you're getting the real thing. You can check several places to get a general idea of what your pill may contain: www.ecstasydata.org www.dancesafe.com www.pillreports.com
The experience I can only describe as feeling completely free and almost humble god-like.
Music sounds especially good on ecstasy.
http://www.erowid.org/chemicals/mdma/mdma.shtml

If your pills contain MDA or MDE or a mix of MDxx's don't fret so much, the effects are very similar and even prefered by some over MDMA, though MDMA is more potent.