I love the humour and crack. A lot of the lines are really great. I think it got a little uneven in spots though, trying to make a jump from humour to tender drama and back again. Also, as others have said, the sex scene in the middle was kind of gear-clash. I think it would have been improved if you stuck with UST and kissing and Draco flipping out over Harry having a hard-on. The hair-cutting itself was fine.
These are my favourite bits:
"Don't tell me to fuck off. I'm not the one who named my sprog like a mid-range Muggle vehicle!"
"Those birds are treated well! The Malfoys have had white cocks for centuries! We know how to care for a cock!"
He felt like a princess. Or at least what a princess would feel like if she were a boy who wanted to ask another boy out on a date after sucking his cock. Make an animated story out of THAT, Disney.