Grammar/Spelling: Okay, so, I think I've mentioned the possibility that you might want to get a Beta-reader. I'll mention it again here. :] You've missed quite a few apostrophes, there are some issues with capitalization, and we have some mixed up usage of "then" and "than." So...once those are fixed, you'll be good on the grammar-front.
Continuity/Clarity: Okay, so I just have a couple of things to mention here. First is about Madam Pince. Every time she speaks in this chapter, you say that she "squawks." Which is a great word, don't get me wrong! But overusing it makes it boring and repetitive. Try varying that with other words. :] Secondly is when you're talking about McGonagall. You call her "Headmaster," but since she's a woman, it would actually be "headmistress." Just so you make that clear to your readers. :] And, lastly, this may just be a preference thing--McGonagall says that Draco is the "brightest wizard of his age." Which just...well...doesn't really mesh. I think Harry even gets better marks than Draco. Though, for the purposes of your story, I suppose that one can slide.
Characterization: Okay! So we have Hermione, Draco, Madam Pince, and McGonagall in this chapter. Madam Pince was great. I loved how concerned she was for the library. And Professor McGonagall was quite good, though I don't think she would have been angry with Hermione or threatened her with detention. What Hermione did was an accident, and Draco WAS trying to use the Cruciatus curse on her...that's more severe than anything Hermione may have accidentally done. Hermione herself is pretty good. I like that she feels bad, but she's not super friendly with Draco yet. Draco is hilarious! I felt like he was high on drugs! It was great. I actually laughed aloud during this chapter. Well done!
Descriptions: Okay, I've gone on my detail-rant to you, so you've heard it. Try to describe the scenes, characters, facial expressions, etc. better. It will really bring the story to life.
Emotions: I think it may have helped a lot if I could have seen more of Hermione's remorse for what she'd done. She really did just change the rest of Draco's life. And I feel like Professor McGonagall would have been more concerned and exasperated at the situation.
Plot: WOW! What a crazy chapter! I'm excited to read the next one and see what happens. You'll have to be careful with this story though. As many writers accidentally do, there's a tendency to move too quickly when forming relationships. Don't rush things or it won't be believable. :]
Interactions: Hilarious Draco/Hermione conversations. I felt so bad for Draco. He's so ditzy and clueless. Hermione's patience is going to be up soon, though, I think. The one thing that was a little weird is when Draco gave Hermione flowers and told her she was beautiful. He's just lost his memories. I think he'd still be scared and confused, not already flirting with a strange girl.
So far, so good! I'll read the next chapter soon. Keep up the good work! :D