I decided to start with book one, despite the fact that it is covered by the movie which I had just watched. In the beginning, it was a slow read because I was familiar with much of the information. As the book progressed, I found minor discrepancies in the movie, and I also discovered new details.
I believe the book does have some theological problems regarding the end times. However, since I am not as well versed in my eschatology as I would like, I cannot enumerate them for you. This book has been good for me in that it has raised questions in my mind and encouraged me to find the answers in the Bible. I now have a desire to better understand the events of the end times. Regardless of the probable theological issues, the series is good, and it will cause you to question things to come. I would recommend the Left Behind books and encourage you to read the book before you watch the movie.