I agree with Rusty, who replied much before I finished writing this, by the way.
@Manuel: I mostly agree with you about the fact that one cannot neglect the formal side of learning. Personally, I find that learning grammar is essential for proper expression.
However, the idea behind "learning like a baby" has been widely misunderstood.
What is usually meant as learning "like a baby", is simply to relax your mind and accept things the way they are ("as is", like software), without questioning everything or trying to translate and understand each word, or your fluency will be hindered.
When you're asked to learn "like a baby" in total immersion programs, your learning as an adult will obviously be much faster because you have a huge background, so you can make connections and get structures right quicker than a child, who needs to gather experience in order to apply rules correctly.
Learning the formal rules of a foreign language certainly will give you more confidence and even more elegance when you speak it and write it. Still, if you have studied in a classroom, you might agree that one cannot neglect the fact that you don't really depend on grammar rules for reacting to basic situations by greeting someone, asking for food in a restaurant or finding your way to the nearest newspaper stand.
Different aspects of learning a language always go together for an adult student and that's what makes the process richer and more enjoyable.