First, he pissed all over the "doing politics differently" line which he'd promoted. This was probably inevitable since any politician who has ever promised to "do politics differently" has eventually realized how difficult it is to actually do that.
Now, after building up an immense amount of media goodwill during the election, Harper has decided to use the old John Diefenbaker approach of going to war with the media. I'm not sure why he's doing this, but it strikes me as an extremely foolish strategy on his part. People can complain about a "media bias" all they want, but it's hard to complain when the individual brings it on themselves.
UPDATE: Paul Wells dives into the debate with a lengthy, but very clear post on why this is a problem.