1300 years on one of the world's major civilizations in 178 pages... yeah, it's pretty dense. Even sketching the outline is incredibly complex, like a huge wall of geometric Muslim art that is exquisite in detail but doesn't resolve into a pictorial whole. I am not fit to say whether he does it well, but he is one of the most highly respected western historians of the Arab world.
Lewis became controversial late in his career when he became an advocate for policy, which is an alluring trap for the celebrated historian, I'm sure, but always a mistake. He consulted with Darth Cheney and other neocons in support of the invasion of Iraq, which is unforgivable, but I don't think it damaged the reputation of his career-making historical writings. He certainly seems fair to me in this book, showing appreciation for many great Arab achievements in governance & culture, and noting how far advanced the classical Muslim civilization was over Europe for several hundred years. It's not an outlying claim to make that the Arab world is now in crisis and not adapting well to modernization.
I of course prefer the vivid specifics over the grand overview. There's some great stuff on slave rebellions and some choice quotes from Muslim scholars. I was very interested in the roots of Wahhabism, which reached farther back than I thought, into the mid-17th century. And I'll always read anything I can find on Hassan-i Sabbah and his assassins.
The book was last revised in the late 1960s, so a lot has changed since then, but his closing remarks seem right on the money, clearly foreseeing the turmoil to come, most of which is rooted in Western imperialism/economic expansionism and its attendant culture shock.
Now I want to read something of similar quality that's more up to date. There are a dozen different roads leading from this, any of which would be fascinating.