I was pondering the same thing; also, I wonder whether not being a native English speaker makes it easier or harder to read it - English is my third language and I found I could read it without any problems.
I think I've read somewhere that reading is basically done by the brain registering the first and last few letters in a word, then just checking whether the ones in the middle are more or less what you expect and where you'd expect them. (In other words - if the start and/or end of a word is altered, your reading speed and comprehension should take a nosedive compared to just messing with the letters in the middle)
If there is some truth to that, it would go a long way towards explaining why we can read it with as little trouble as we do.
I think I've read somewhere that reading is basically done by the brain registering the first and last few letters in a word, then just checking whether the ones in the middle are more or less what you expect and where you'd expect them. (In other words - if the start and/or end of a word is altered, your reading speed and comprehension should take a nosedive compared to just messing with the letters in the middle)
If there is some truth to that, it would go a long way towards explaining why we can read it with as little trouble as we do.