From what i've read I think the correct decision was made. Amanda Knox told too many different stories. It would have been good if they could have videotaped her police interviews though

It does sound plausible that they may have been high on drugs ( it doesn't sound like they would have done this sane ) and forced Meredith to take part in a sex game and then killed her after she was raped and started screaming

The actual killer was decided to be that drifter - I think if Amanda Knox had have just told the truth about what happened she might have received a much lesser sentence