The area that the Fremont Street Experience is located in is pretty sketchy, but the Viva Vision canopy LED screen was probably worth the paranoia I felt while walking there from 7th Street where I was parked (street parking free after 6 pm). The LED show I watched was the alien one. It was pretty impressive, but the Fremont Street Experience is really just a 10-15 minute experience.
Parking is NOT free in the FSE parking building - something like $1 per half hour or $10 the whole day.
Seems like the casinos here are a little more crowded in terms of the spacing between machines. I felt pretty claustrophobic in the Fremont Casino while trying to get to the restroom.
I think FSE is fine for one visit, but not worth repeated visits like The Strip.