I think boost is a great library. I love it. My favourite library is boost::bind and boost::function, which make function pointers much more flexible and easy-to-use. It fits in very well with different frameworks and keeps the code tidy.
I also use different Boost classes. For example, I use boost::graph to create graph classes and I use boost::filesystem for working with files inside directories.
However, boost is very complex. You need to be an experienced programmer to know its worth. Moreover, you need to have atleast some experience in C++ to understand how Boost works and implications of using Boost here or there.
Therefore, I would highly recommend looking at Boost for experienced programmers, especially if they are trying to re-invent the wheel (again). It can really be what it says on the tin: a boost towards your goal.
However, if you feel that the person asking a question is a beginner and tries to understand (for example) memory allocation, telling him to try boost smart pointers is a very bad idea. It's not helpful at all. The advantages of smart pointer classes, etc. can be comprehended only when the person experienced how standard memory allocation techniques work.
To finish off, Boost is not like learning to drive a car with automatic gearbox. It's like learning to drive on a F1 racing car.
