Presuming that we are talking about the socially accepted versions of extrovert and introvert (ie related to energy and people) the chart seems quite astute.
I've been thinking about that particular scale recently and have had my definitions questioned in light of my own type being questioned.
Introvert is usually thought of as more reclusive and less bothered with interaction. They are expected to be more passive than agressive and thought of as self contained, as much as a human can be. However if you think of introverts as living, by preference, in an "internal world" some of the confusion can be overcome. There are those introverts who will seek people out but usually these people are those who have something which will add to the internal world. Hence an introvert with an enthusiasm for comics may well seek out fellow comic lovers, be these others introverts or otherwise, to feed the internal world of comics which they carry around in their minds.
With this in mind I was thinking myself about ENFPs who seem to spend so much time in quite introverted thinking despite being quite the attention seeker in many a case. The thought which occurred to me was that perhaps the ENFP is pulling in information to affirm their current viewpoint as many seem to lack the requisite critical thinking (not that I'm asserting that ENFPs lack in intelligence or anything of the sort, just a weakness perhaps in this one small area) to esablish firmly their own definitions for what is right and what isn't... or what is the best path ahead. Ergo although they are extroverted in that they network and are generally quite open and friendly they spend quite a lot of time sucking in information and establishing an internal world as a guide to their actions in the external world.
As for the list as posted in the opening post, I can only nit pick. In general I find nothing wrong with the list. I am rather surprised to see ENTJs so far up the list but upon further analysis I can only conclude that their focus upon the external world, mostly to the detriment of the internal world, is about right. They establish what the external world should be and set about directing it's course. The same is true of the ISFJ, although mired quite often in the expectations and "supposed to's" of society they also emit such expectations with the thought that if they abide by it then so too should others.
I do however have the nagging feeling that there's a problem with the list. As with many of Wildcat's writings my mind is drawn more to the larger picture and is distracted from such analysis of detail in focus. My concern is that in studying whether a particular type is more extroverted or introverted we are ignoring the wider implications of their preferences. ESFJs may well be extroverted but the foundations of their self image may well be routed quite firmly in the INTP side of their personality, hence the more solid appearance when compared to say an ESTP or an ENTP. This logically suggests more effort devoted to the introverted world and therefore does it not suggest that the model of a simple list does not do the full picture justice?
As with all detailed studies I can only conclude that the list is correct within it's context and useful as a case study but perhaps misleading of the overall picture.
Mind you though it's something I'd not thought of. I was intending to write a new thread based on extroversion versus introversion and the disparity between what people see as E or I versus what it actually is in terms of cognitive wiring.
) experience. The ENTP and ENFPs I know are definitely more extroverted than the ISxPs. My ISFP bf and I are both pretty introverted, by pretty much whatever definition you want to use. Definitely more than my good friend who's an ENTP, or ENxP acquaintances. We might like to go out and party or whatever in short doses, but it's always a relief to come home again. 
