What did you think of the ending?

Its funny, I was thinking that when she laid down next to her, how much she was screwing around with what would later be a thoroughly-checked crime scene, and how it was going to work out that her friend could have murdered him when she'd been drugged. I don't get it, really, but...it turned out the way it turned out, so I've long ago learned to just go with the flow with this kind of stuff.
I mean, they would have found out right off the bat if she couldn't remember, right? Quickly enough that a drug test would be in order, you'd think. Google says Rohypnol stays in the blood for up to 60 hours...so...anyway, moving on lol

The ending...she tore up the letter? Kind of seems like she ended up being the villain of the movie. Sure, the guy was an a-hole, but not only did she kill him and frame her friend, after her friend took the fall and she'd gotten what she wanted out of her, seems like she just wiped her hands of her.
Her friend (man I suck with names) was the true sociopath, but the murderer-girl was driven enough by selfishness to end up the worst of the two.

I'm sure there's a lot more meaning that I'm not getting, what with the dreams being explained at the end, but just finished watching it a few minutes ago and that's my take so far.

I've been looking forward to seeing this, I thought there'd be a little more...something to it though...depth, maybe. Seems like one of those movies you'll forget about in a week or two...there's really nothing about it to root it in your brain, you know? Nothing stands out...nothing to anchor it, no real moving scenes, really.

The movie is a good example how to tie loose ends and finish up with a story and still leave a lot of room for interpretation. I too thought the roofied girl would let her go with the plan and then report to the police she was drugged which could have at least give her a room to fight for innocence. However, we're often told by her she doesn't have feelings... so I'd say it's very likely she admitted to the cops right away. I don't know what the procedure is, I guess the forensics and police should do their job and let the proofs tell/confirm the story first. But one can argue, this is an upper-class house/family, cops are busy/don't care, so why bother with what seems to be a straightforward case.

Also, the main protagonist seems to have developed a thick shell by the end. Of course, we should assume she cleaned herself, hid (and burned later) the clothes, and made the scene when calling the cops. Also, we don't know with certainty the main protagonist has or has not improved The Technique, so we don't know if her tears are real in the kitchen scene (I'd guess yes) but towards the end of the movie the main protagonist is getting progressively emotionless. So we need to take that into account when we imagine her report to the cops. Or maybe she let her mother come and do the report.

I like the way we have options to fill in the gaps, without the movie forcing us into a matrix, but still completing its job of wrapping up the story. It only shows us the "facts" what the characters did or did not, but doesn't tell us what to think about them.