The books are smart, and the illustrations don't just act as punchlines or to rehash what's already gone on in the prose—as in The Absolutely True Diary of a Part-time Indian, they serve to forward the story and the character development. Greg is an imperfect protagonist: smart but almost entirely unmotivated, a boy who doesn't appear to have an altruistic bone in his body, who occasionally acts ABYSMALLY towards others (and doesn't usually even entirely realize it), but who's easy to relate to and is almost always likable. The secondary characters are, like him, imperfect but mostly likable (especially his mother and Rowley, but even Rodrick, who just KILLS me).
As is the case with the traditional comic format, since Kinney forces the reader to rapidly alternate between mediums, they're deceptively complex reads, which makes me all the happier that they're so popular with reluctant readers. (Very sneaky, Mr. Kinney!)
They capture the day-to-day triumphs, embarrassments, and injustices that a middle school boy experiences (and in that last case, occasionally doles out), and they're mostly realistic and believable in a tall-tall kind of way, but more than anything else, they're FUNNY. Like, laugh-out-loud, shake-the-bed-until-Josh-is-forced-to-stop-reading-his-own-book-to-see-what's-set-me-off-this-time*, read-the-books-over-and-over-and-over-again-until-they-fall-apart FUNNY.
Anyway, I'm sure you already know all of the above. So really, what all of that boils down to is this: I JUST NEEDED TO SQUEE.
I think it was probably the name of Rodrick's band that finally tipped him over the line from finding the books Amusing-by-Proxy to Actively-Interesting.
I tried to play it cool, but I might have tipped my hand by tackle-hugging him and squealing, "ARE YOU GOING TO READ THEM? ARE YOU? ARE YOU? THEY'RE SO MUCH FUN, I KNOW YOU'LL LOVE THEM! HERE, LET ME READ YOU MY FAVORITE PARTS!!"
Hopefully I didn't scare him off...