Visited Philadelphia using CityPass over President's Day weekend, which in retrospect was a big mistake considering the crowds, but in any case...
My GF and I are both avid Science Channel watchers and enjoy museums, and hence expected FI to be the highlight of our trip. The moment we walked in however, we were inundated with the sights and sounds (or rather, visual overload and din) of what seemed like must be at least a thousand kids rampaging through the facilities. It was like the scene when Arnold first walked into the classroom in "Kindergarten Cop", but multiplied a hundred fold. Not a hyperbole either.
Thank goodness we had CityPass and was able to bypass the communistic/Great Depression era soup kitchen-ish line. Alas, that turned out to be the best part of our visit.
If you are an adult hoping to enjoy the museum on days like this, forget it. There were massive lines everywhere, and yet there's no point waiting in any lines because rude kids will just squeeze/shove right in front of you anyway...what are you supposed to do, yell at/explain the societal principles of queuing to kids?
Unlike more adult-oriented science exhibits in other museums (e.g. Fernbank in Atlanta), the exhibits here are little more than a large assembly of over-sized, hands-on toys, with little to no emphasis any of the underlying scientific principles. Want to learn about Bernoulli Effect? Here strap on a couple of wings and stand in front of a giant fan. Want to learn about mechanical advantage? Here are some weights for you to pull. Want to know about pulleys and gears? Here are some crappy broken gears for you to assemble and hope they lead to something interesting. You get the point. The focus here seems not as much "how can we educate the public about the fundamentals of science", but rather "which fundamental scientific principles can we use as an excuse to make rather lame oversized toys out of in our gigantic amusement park for kids". Wow that really came out sounding waay harsher than I meant to...it's true though.
Oh and 10% of the stuff are broken anyways.
I'm sure it's great for kids. If you're an adult (sans children) though, avoid.