I did, though mostly secondhand (I had a couple of classmates who were into them). My main exposure to them was via an evangelical's huge multi-year writeup dissecting exactly why they were awful.

These things sold tens of millions and informed a huge number of Christians' religious views. Some highlights include:

• The very first words of the very first book are "Rayford Steele's mind was on a woman he had never touched. With his fully loaded 747 on autopilot..."
• Russia and Ethiopia fire their entire nuclear arsenals at Israel. This is because the authors see it as fulfillment of the Bible verse discussing "Gog and Magog." Divine intervention destroys every single missile and aircraft with no Israeli casualties. Somehow, this does not cause any of the characters to question their own religious beliefs.
• The Rapture happens. Billions of people vanish overnight. Somehow, this exact fulfillment of the Rapture prophecy is treated as something between "Huh. I wonder if the Christians were right" and "That's just a kooky Christian theory, it was actually caused by the electromagnetism from nuclear weapons."
• Less than a week after The Rapture, the world gets back to normal despite something like a third of the Earth's population having just disappeared. There is no sign of long-term trauma or logistical strain.
• The Antichrist is a Romanian who takes over the world by ascending to the position of UN Secretary General. His evil plan includes dismantling the world's militaries and using the money saved on weapons to pay for the development of the Global South.
• Female characters have two possible personalities: perfect tradwife and sinful harlot.
• One of the later books includes a graphic, gory description of Jesus simultaneously exploding tens of thousands of people.