Is that pretty teen oriented, or could a couple adults have a few good play throughs?
Good question. First off, apparently as with Evermind's game, you are trying to solve a crime. It's a one-and-done game, there is no replay value. It's not a game like Clue; it might even be best to not think of it in terms of a "game" but more of a challenge.
Answering your question in two parts, 1) Gameplay: I've only played this one game in the series, but it is definitely appropriate for adults and teenagers. There is a level of deduction and reasoning involved. 2) Thematically: Oh boy, I played this with my 11 year old, and without giving anything away, the story for the Jamie Banks case involved rumors of a high school student fooling around with an adult, and an organized sports gambling ring. Did not anticipate having to discuss point-shaving with my kid!
To start, it was just me and her one night; we spent an hour or so reading through and examining all the evidence, and another hour discussing topics, considering hypotheses, and revisiting documents. Eventually we realized we had.... no idea how to complete the first objective. We decided we were spinning our wheels, and we should put it away for the night, let it stew, and come back fresh another night. I worked on it by myself periodically the following few weeks, and didn't get anywhere. She and I would talk about some ideas until I finally said to her we really needed to sit down and complete this game before we totally lost interest. It was fulfilling, but I shouldn't have let so much time pass between starting and completing. And I am indeed kicking myself for not seeing the necessary clues on my own.
Could you finish the game in one night? Sure, but you'd need to commit a few hours to it, and decide if you were going to resolve to finish it in that one sitting, even if it meant getting online help.