I liked the difficulty level. I couldn't figure out how to unlock the last two places and it was driving me crazy though.  I think that the mechanics for going through evidence on the desk was a little user unfriendly.

Also! I kept trying to unlock the last places, so I didn't realize that when you Solve the Case, you also use the clues to identify the culprits.  I think that wasn't very obvious and I was worried that clicking Solve the Case would lock me out of further investigation, so I clicked around a lot before finding out how Solve the Case worked.