To be honest, I read The Vision of Piers Plowman mainly to see if I could. I wanted to see whether I would be able to understand the text without really studying Middle English. I think I did pretty well, though I'm sure there were subtleties I missed. It was definitely an advantage to know Old Norse, since I was able to port over certain words from there. But overall, I found it read pretty well to my modern-English brain. There are also frequent interjections of Latin, usually from the Vulgate Bible. It was striking, in the midst of what seemed like primitively spelled English words, to suddenly see lines of perfect Latin.
In terms of the content of the poem itself, I found it repetitive and unexciting. There is much use of moralistic allegory, with characters like Dowel (Do-well), Dobet (Do-better), and Dobest (Do-best). Someday I would like to go through it again with a good commentary, as I think I will get more out of it then.