The post is interesting to explain the different techniques to use in learning a second language. Although, for people that learned more than one language, a lot of the theories given are logical.
I learned English late in life and it is an evidence for me that I did not learn French the same way that I learned English. The syntax, the vocabulary, the grammar are so different that it does not associate the same part of your brain.
Neurological researches showed that when a person is speaking one language, some connections in the brain "lights up" (study under MRI) and when this same person switchs to another language, some other parts of the brain "lights up".
None the less, it was showed that there is also a connection between speaking more than one language and intelligence.
It is a pretty good argument to learn another language, don't you think?