Free

Isaac (I flew with him) did a great job of summarizing the microgravity experience so I'll just give my 2 cent plug.  The most honest opinion about the experience is that it's so unique that trying to explain it with words simply cannot do it justice.  I used to think that the experience would be much like floating around in a dream - it's not even close.  Yes you do float around, but your head and muscles just feel different.  To be free from the effects of gravity, even for short spans of time, is an incredibly liberating feeling that you'll *never* forget.  I don't want to think of the experience as floating because activities like swimming or parasailing both involve floating - zero g's isn't about floating, it's about freedom :-)