"Wow, is that what a light novel looks like?" To address your surprise, I suppose we should answer why the books are classified as
light novels in the first place. What exactly does the term "light novel" mean?
A
novel, as you know, is a work of prose written in book form, usually covering a minimum of 180 pages. (Smaller books tend to be called
novellas in English literature, e.g.
The Old Man and the Sea by Ernest Hemingway is a novella, not a novel. So too is F. Scott Fitzgerald's
The Great Gatsby. Too long to be a short story, but too short to be a proper novel.)
The word
light is used here to reflect the reading level of the book. Light novels typically have for their target audience Japanese teenagers. Why?
(1) They are too difficult for small children to read. Teenagers, young adults, and older adults can handle them.
(2) The subject matter is often times a little too immature for older adults' tastes.
(3) The manner in which the book is written is more suggestive of transient storytelling and less suggestive of creating a masterpiece, i.e. the author does not usually strike you as being as skilled with the pen as were Dostoevsky or
Souseki.
Wikipedia has more to say on this, but the take-home message is: the stories in a light novel may be very entertaining, but the caliber of the author's writing skill is (typically) much lower than one would expect from a master of the pen.
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In terms of what came first ...
1. pre-April 2006 = Books 1 thru 7
2. pre-April 2006 = the first of two manga series is attempted. It fails after two volumes.
3. April 2006 = Season 1 of the anime begins airing
4. June 2006 = Season 1 wraps up
5. Summer 2006 = Book 8 is released
6. ??? = the second of two manga series is attempted. (This is the manga you've probably seen in USA/CAN bookstores.)
7. some time in between #5 and #8 = Book 9 is released
8. April 2009 = Season 2 of the anime begins airing
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How close is the manga to the books? Let's put it this way ...
The anime is 98% loyal to the books imo. It's a very, very accurate presentation of what goes down in the books. They (Kyoto Animation) really did a superb job of bringing the much-loved franchise to life on television. They must have been truly big fans, because they paid
so, so much attention to every single little detail. The clubroom
alone is amazing.
The manga is (from what little I bothered to read) 90% or so faithful to the books and manga. From what little I saw (several chapters of Volume 1, raw, back in the Summer or Fall of '06), all that changed was:
(a) the drawing style. Absolutely horrendous. Not at all like the excellent art done for the books nor like the anime's top-notch character designs.
(b) dialogue. Not necessarily the core message content, but rather who said what when, how they said it, etc. Little things. Little things that can make you have an entirely different impression of a character's personality. :\
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How biased am I against the Haruhi manga? Very.
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How easy are the books to read? I can't read them without constant dictionary assistance. The dialogue's not so bad, but Kyon's narration is (for a non-fluent reader like me) really hardcore. How easy is the manga to read? SUPER easy. Just as easy as a doujin. It's very, VERY easy. If I bust out the dictionary every sentence for the books, I bust it out two to three times tops per manga chapter. It ain't bad.
Then again, mangas have way way way way waaaaaaaaaay less text than books do.