I bought the first four Reacher books without reading any first.
I've now read three of them. They're OKAY, but as I've seen others comment, they're not the most realistic I've read.
To me, Reacher is a bit too tough, for me, unrealistic. The books are readable, but not good enough for me to recommend. I've read a lot better series.
Like Harlan Coben, Connelly and several others much more.