I thought Gravity's Rainbow got more confusing as time went on, if you just flow through it yeah its not too bad. But to fully understand the 100s of characters disappearing, reappearing with new names, etc. I definitely found myself consulting notes in the later pages to remember what role someone had played 400 pages earlier. The earlier chapters you can just absorb with no thought for how it contributes to the whole, by the end it is a lot of threads to try and keep in order.