Definitely something everyone should see. It was absolutely amazing to see how the human body works. The whole self-tour took about an hour to do. That's if you're genuinely interested in seeing and reading everything.
Not as gross as you may think it is. In fact, I went in on an empty stomach, and was starving by the time I got out. Even seeing the Siamese twins didn't phase me.
If you get an opportunity to go, definitely do it. It's only $35, which is basically a 15-second hand in 3-card poker. So it's 15 seconds, or an hour educational tour.