[Edit: Acutally I have one more thing to add - can anyone say loopholes?]
[Edit2: Possible SPOILERS in comments (just in case :))]
Lots of people seem to think this book will close down all sorts of pairings - I think it just gave us canon that is far more likely to produce them. Yes you have to work a bit harder, but there was so much more character interaction in this one. For a start Draco was human - he had depth, he was not 2D and Snape gained depths as well. I can see whole lots of D/H and Snarry coming from this.