Link goes to Amazon page.
You can use Amazon's "Search Inside" function to see the relevant text about Dawn and Connor.
A small excerpt:
There are many reasons why Buffy the Vampire Slayer (BTVS) and Angel are two of television's brilliant jewels, and most of them have their origins in the contributions of creator Joss Whedon... So it's all the more shocking that a writer so astute, with such an instinctive command of what works and what doesn't, would twice fall into on of TV's original crap traps - the introduction of a snot-nosed brat...
And specifically about Dawn:
Along the way, Dawn's "Key" status takes a back seat to her status as a pain in the butt.
Despite his undead heritage Connor (Vincent Kartheiser) was not a vampire, which was regrettable since someone surely would have staked him soon after his first appearance...
Other "dumb" events in television history: "Spock's Brain" from Classic Trek; American Movie Classics going commercial; Janet Jackson's wardrobe malfunction; the quiz show scandals of the 1950s; the final episode of "St Elsewhere"; Scrappy-Doo; three networks/three Amy Fisher movies.
And the winner, the dumbest moment in the history of television? The Star Wars Christmas Special!