My rating: 3 of 5 stars
I read the original edition (1918) which is in public domain now (one good and properly hyperlinked version can be found at http://books.cat-v.org/writing/elements-of-style/.
Three stars because much of advice regarding English usage in this book is outdated now. I am aware of the expanded edition by Strunk and White but even that edition is from 1959; I doubt I will gain a lot by reading it. However, I will not mind skimming it sometime.