UnholyUrine is right - all tests like this exhibit the Forer Effect to some extent. Also, this sort of test is supposed to indicate your sort of "native" preference for cognitive functions. The 4 letter code is often misleading and the theory is more complex (but not much).
Let's break down INTP, which a lot of us got in our results. Basically, according to the theory of psychology behind this kind of test, everyone has preferences in two main areas - Perception and Judgement.
There are two types of perception: Sensing (S), and "Intuition" (N)
There are two types of judgement: Feeling (F), and Thinking (T)
These functions can be further modified by the letters E and I, which dictate whether the function is concerned mainly with the external world, or a person's own internal world.
The letters P and J simply tell us whether a person uses a perceiving function when dealing with the external world, or a judging one.
So, INTP:
Dominant Function: Introverted Thinking (Ti)
Secondary Function (governed by the "P") Extroverted Intuition: (Ne)
Tertiary Function: Introverted Sensing (Si)
Inferior Function: Extroverted Feeling (Fe)
That basically goes from strongest to weakest, and they all interact with one another. Often the dominant function will attempt to make up for or smother the weaknesses in the inferior function, for example, and the secondary function plays the role of feeding information to the dominant one for processing.
In INTP, Fe is the inferior function. Practically speaking, this means that the kind of situations a person will have the least preference for are social situations where they have to empathise and adhere to social norms. If placed in a social situation the person will likely resist using Fe and instead rely on Ti, and probably come across as slow and awkward. If this person feels way out of their comfort zone then they're probably being forced to use Fe. Where Fe does tend to express itself spontaneously is when Ti can't deal with something effectively and rationalise it - this leads to sudden outbursts of rage and emotion which are otherwise out of character. An example could be the breakup of a relationship.
But no, it isn't good psychology. It is interesting though.
None.