Deader Than Disco: Now that the controversy has died out, the book is significantly less popular (minus the title, of course).
Seinfeld Is Unfunny: It would probably be seen as a very tame book by today's standards, but the frank and open depictions of puberty (although common for Judy Blume books) were seen as controversial and perhaps even obscene in the 1970s when the book was published.
The Woobie: Norman. He's a genuinely nice (if a bit nerdy and awkward) guy who has a very sweet crush on Margaret, but she wants nothing to do with him, partially because he's so unpopular (she is a preteen girl, after all).
His family seems to be pretty rich though. They live in a huge house and have a maid.
Spoiled Sweet I say. There is also Laura Danker, who deals with boys bothering her over her breast size and the other girls envy of her, which leads to nasty gossip about her being a slut. She is just an average 12 year old who attends mass and confession regularly.