First of all, don't feel bad that I didn't label anything 5 stars--to me, five stars means nothing can be improved at all.
Although I gave technique the lost score of the four values, I wouldn't say it's at all bad, or that this isn't nice looking. Your art is colorful and attractive, and stylistically sound, by which I mean that while it's not a super strong match for the show's style, the differences do look like they're a question of style, as much as skill. It's doesn't look like you couldn't draw the characters; it looks like this is simply your way of drawing them. It also shows that you didn't just use someone else's vectors--this is very definitely your work, and while it's not flawless, I certainly enjoyed the drawing, even aside from the humor. In particular, the expressive faces fans are so fond of in FiM shine through here.
Speaking of the humor, it's well done. Dialogue isn't wasted on unnecessary set up, but the joke isn't under done in any way either. The foreground humor is the sort that would just earn a gentle smile--it's cute, mildly humorous stuff that plays well on Twilight's fanaticism for reading, and her frequent failure to realize that most ponies don't share her passion. The joke didn't make me laugh out loud, but it made me happy--adorkable Twilight indeed.
The background joke is what really stands out in this comic to me. Since "Read It and Weep," we've seen a lot of Rainbow Dash with a book in comics, both as the focus, and just for flavor, and initially, I thought it was just "Oh look, RD's in the library too, cute." With no need for dialogue at all, your second frame makes clear that something's up back there, and Rainbow's wings popping up did a good job of conveying excitement without drawing too much attention away from the foreground. What I really loved, though, was the annoyed librarian chasing them out. That's the source of real laughter in this comic. I loved that. You've got this whole foreground, and it's sweet and mildly humorous, but in a way, it's just a diversion for the real joke.
That diversion is why I gave 4.5 stars to impact. You did this comic on two levels. Both are worthwhile on their own, and different people will enjoy different a different "side" of the comic more or less than the other, to their own tastes. The way each is completely independent, but supports the other side, is what makes the comic special and unique.
On a less objective note, I love the librarian pony there, and can't say why. She's just awesome.