I am currently reading the Yusuf Ali version (as I do not speak arabic - although I am trying to learn) and so far, so good. I bought it because it came highly recommended and reviewed on the amazon site.
As a translator (French/English), I can tell you right away that no matter how hard you try, translations are never 100% perfect (or rarely), this due to many reasons such as expressions, sayings, cultural influences, etc. A certain word in one language might be completely acceptable, but the closest translation in another language might, for some reason, have a negative connotation associated with it.