It is very good for what it does, which is advise on how to write clearly and concisely. But generations of writers have completely misunderstood its purpose and used it as a Bible of Good Writing. It's not. Linguist Geoffrey Pullum has famously gone on something of a
crusade against
The Elements of Style, and while he makes good points, it may be a little unfair to blame S&W for the fact that writers don't realize the original authors were addressing an audience of barely-literate college students. If you are a fiction writer, S&W's advice should be taken with a very large grain of salt — if you try to write novels using
The Elements of Style as your guide, you will probably write very cleanly and correctly but very badly.