1) Morgan Freeman basically gets paid to do exposition in movies. That's so crazy to me.
2) This chick is retartedly powerful, dear goodness. That's crazy.
3) I really, really like this. Limitless comparisons seem apt. Not feeling the hate for this. If Luc Besson is a bad director, he's a bad director that makes great movies.
To look at it another way, I think this movie was very savvy in saying that "we only use 10% of our brain's capacity" instead of "We only use 10% of our brains." While the myth you're talking about is easily addressed, can you really say that we are all using 100% of what the human brain is capable of?
If you were in a college course and I were your professor, i'd make a simple analogy: Do you use 100% of your house? Most likely you'd say yes. Then I'd ask are you using 100% of it's capacity? Most students would want some clarification because the obvious answer: no, would show them wrong, or force them to acknowledge that they did not respond to what was said, but instead what they thought was said, so I'd elaborate with further questioning: Is there any way you can use your home more efficiently? More profoundly? More influentially? Can you add things to your house to make it better, or is it already fully in use, working at full capacity, with no room for any improvements?
The idea, that additional powers are locked away in the mind is a very common one in fiction, especially where super powers are concerned. These powers escalating independent of personal skill and being ranked on a percentage scale is relatively unique, but hardly flies in the face of modern science.
That is, unless you ignore the word capacity, in which case, it makes no sense.