Started: March 9th
Finished: March 31st
My excuse for taking so long over this one is that it's a little book. It vanished for over a week at one point because it was skinny enough to hide under a single piece of paper.
Summation: it's prescriptive, it's funny, and it's out of date. Or at least the edition that I read is. Time has passed by many of the specific usage rules. Imagine describing Web 1.5 without using the word "personalization".
On the other hand, the advice about clarity and brevity is timeless. "Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines or a machine no unnecessary parts." "...although there is no substitute for merit in writing, clarity comes closest to being one."
There, saved you from having to read the whole 85 pages. :-)
But seriously, despite the criticism I've been newly conscious of my writing ever since I finished it. I think that's actually a good thing. It's never a mistake to check that you're saying what you mean, clearly.