My summary from Mr. Masahiko NOMI's book "Ketsueki-gata Josei Hakusho" (Blood-Type Woman White Paper).
There are both frank and unsociable type Bs. Bs are retracted like the latter, or acquires attitudes without greetings like the former -- it is hard to acquire the manners and greetings that suits to the surroundings and the society. Everyone easily understands Bs are familiar, do not discriminate and believe people, before long. Openness is a common property of type B.
Type B, contrary to type A, is the least conscious of the world and the surroundings.
As type B is not conscious of surroundings, B's going-my-way behavior comes out. It dislikes to be complied with minor rules, restrained and constrained, extremely. Strong interest means full of enjoying heart. A type-B person does not consider profit and loss like type O or it does not calculate worldly value like type A.
As B's interest is directed towards the external world, thoughts become scientific and practical as it respects facts. Type-B person is not influenced by common sense or customs, so it has wide and flexible comprehension power.
Type B is not stable. Even if it is seen as stable, whether or not it is moving a body continually, it uses its brain rotates swiftly. Type B's emotion changes sensitively. It is able to comprehend other people's situation and have interest without subjectivity. So B is compassionate and sometimes takes an action swiftly.
However, type B's emotion is not strong. It only seems so, because it expresses and does not restrain when a feeling breaks out.
Although B sometimes clings to the its thought terribly stubbornly. In this case, Type B shows stubbornness.
Shigeyuki Yamaoka (2001), A Psychology Book for not to Become a Useless Adult
Self report of personality from 1 (strongly disagree) to 5 (strongly agree); Subjects are 649 university students who love blood-typical topics.
Actually, there are not much type Bs around me, so I haven't confirmed all the above description yet. But I feel a little bit easy when I am with type B (I am type AB). I need not to care when I am with type B, while I need to be cautious, to some extent, when I am with type O and type A. Although it largely depends on a person.