Machine translation of Japanese is crap compared to languages that are more similar to English. On top of that, the writing in Rewrite is filled with a lot of clever and not-so-clever puns, which makes it hard to translate even for humans. For example:
My opinion is that poor translations (machine or otherwise) ruin the mood. If you're reading for educational purposes (say, learning Japanese while playing an interesting game), I'd say use every tool at your disposal to try to understand it. But if you're playing purely for an entertaining experience, then I'm with Elvin: you're going to get a lot more out of the game with a carefully written and reviewed translation than having to stop every sentence to mentally correct a poorly written one.