I've read most of the Jack Reacher books and have the others on my shelf ready to go.
I have the show lined up to watch but I'm apprehensive because I have this idea of what the character is like and matching that on-screen will be hard. Cruise was no Jack Reacher to me, both in terms of physical stature and character. But that being said, I still enjoyed it but couldn't link it to what I saw as Reacher.
In terms of his size, it's integral in a way. The whole idea is that he's this larger than life presence, an ex high ranking military police Major that was brought in to solve the crimes no one else could whilst also being able to hold his own and is now retired and travelling across the country he dedicated much of his life to protect. He's basically an unstoppable juggernaut but has a more sensitive side which would be tricky to show on screen without going down the stereotypical path and in the books it's more about the internal dialogue which reveals these aspects.
I'm glad it's been renewed, I assume that means it's done quite well. Season 1 is based on The Killing Floor, which is the first book in the series. Perhaps the second will be based on the next one, Die Trying. Although saying that, apart from the odd non-integral storyline they can typically be read out of order. I buy them from my local charity shop and just read them as I come to them, so not in order at all, but they all still make sense and I have never been confused by any missing elements.
I'm just finishing up "All Of Us Are Dead" on Netflix then will move on to Reacher