A couple disadvantaged are the migraines that is can cause. And it can cause eye strain there are alot of things that could hurt your eyes. Like being in virtual reality for to long. It can very rarely make you go blind.
When Pi tells the second, more brutal account of what happened, the reader understands how important storytelling is to Pi and how changing the events into a story helped him survive. Furthermore, we can see how Pi had a will to live even in the face of certain death.