With all of the letters, this chapter felt a little empty to me. I always think of Harry as someone who isn't much for writing letters. He, like Ron, seems like much more of an "in person" sort of guy.
That being said, I liked parts of this chapter, primarily Harry's written conversation with Cho. I thought having Luna call Sirius Stubby Boardman wasn't a very good idea, though. She called him Sirius at the end of OotP, and this makes her seem a bit insensitive to Harry's pain. OotP Harry certainly would have exploded in anger after reading that. Glad Harry's moved on from all that anger.