Linear.
No matter how many times you play through unfortuntately, the same people will die in the same methods, and you will always be sad about it.
The first time through any of these games is really magical for that reason. "Oh boy I really like this character after spending time with them I wonder what else I can learn about the-AND THEY'RE DEAD."
In terms of the mystery angle, it's also much like Ace Attorney in those regards too: While you deal with the drama of a murdered friend and having to find who did it, there's an overarching mystery you get pieces of in each chapter that comes to a conclusion with the last one.
The only real problem some have with the game is the mini-game aspect of trials at times. Most of them boil down to "pointing to a specific piece of evidence and blowing open something someone says", which is familiar if you've played any AA. Sometimes for seemingly no reason though, you'll have to play a game of hangman, or when an accused person "breaks down" you do an almost rhythm game part.