Children pick up languages faster than adults; True or false

So I'm sure most of you must have heard most often than not that children learn languages faster than adults. That it is easier to pick up a language as a child than as an adult. What do you think guys, is this entirely true?

There are many heated discussions on this topic. Some scholars believe there is a phenomenon of "window of opportunity", which closes as soon as a child reaches puberty. This means that children acquire foreign languages as well as accents with utmost success until they turn 12. From that point on, the process of language learning becomes somewhat slower and more complicated. 

On the other hand, it is also believed that children learn everything extremely quickly. They soak up knowledge related to their surroundings, so that may not be limited to languages. 

Learning as a kid is easy as you have no point of reference to other languages. I guess there are other factors too, but primarily a big problem of 2nd language peeps is the fact that they sometimes carry over lexical rules from their mother language to the ones they are trying to learn. 

I am somewhat of that school of thought because when I was younger, growing up with my mum, I picked up on all of the local dialects of the states we lived in because we moved a lot. But as soon as I left for boarding school,I lost them cos I was no longer surrounded by people who spoke those languages as English was our primary means of communication.

Based on my experience, kids learn faster. :) Less barriers, more time, and fresher brains. :P

(I assume you are talking about conversation) 

It depends. If you ask "who can reach B2 in a language faster, a child or an adult?" I would bet on the adult. If you ask "who can learn enough for it to be useful the fastest" I would bet on the child. A child doesn't have to learn much for it to be useful; the bar is much lower. 

I’ve heard this a couple times.. what do you think?