I've been a fan of the Jack Reacher series for years and owned every book up to the point when the ideas ran out. Was happy when they decided to make the movies, but thought Tom Cruise was the worst possible actor that they could have picked for the role. Most fans were outraged. Reacher's physicality is as much of (if not more) a character trait as his background, demeanor, etc. He's supposed to be like a man-mountain. When they decided to start over at Amazon and named Alan Ritchson as Reacher I was thrilled that they had at least picked an actor who physically could do the role justice.
Watching the trailer though, it looks like they've decided to change Reacher's personality which is another disservice to the fan base. Reacher is a man of few words, and doesn't feel the need to show off. He mostly just wants to be left alone, but will get involved in a situation if he thinks he can help someone in trouble. This characterization looks like they're trying to peddle to the masses, not the fans. It might be the right way to gain a new audience, but the consumers that have made the franchise a success will not be happy.
Its just a trailer, so maybe I'm reading too much into it. But I'm certainly not as excited for this as I was before the trailer.