Be prepared for a cheap campy presentation. I guess you have to go as a Roswell tourist, I did, but it's really not anything impressive. I did get a nice shirt at the gift shop.
I agree with Jeeperdon, its just a way that Roswell is getting tourist $. It is interesting that my wife grew up in Roswell and never heard about the "little green men" until she moved away and the city relized they could make $ off them!
My wife is from Roswell and the whole town is covered with alien things. The street lights down town are painted like alien heads. There used to be a bunch of alien stores and gift shops downtown. If you ever get out there check out the Mcdonalds it is shaped like a UFO.