I'm torn, because it was readable and interesting while at the same time being somewhat disappointing, but I don't want to penalize authors for opportunities lost and each chapter is itself interesting and well-written ... but heck, you could have a book, every sentence of which was Art, and yet which was unreadable as a whole. So two stars, and maybe he'll think better next time.
I think I was expecting a slightly different book—one which, for better or for worse, talked about each letter, where it came from, how it changed and developed, its uses, etc., and the book does do this, only it does it for about 2 pages per letter, then blathers on about how usages like (not a direct quote, just evoking the mood): "D goes with W for dwarf and is friends with R but not with L unless inside a word like Kindle" and I skipped all of those paragraphs, and then he moves on to a random essay.
It also, weirdly, doesn't have illustrations, and it needs them. Rosen will natter away about how a letter begans as a lopsided something-or-other, gets turned around by the Phoenicians, inverted by the Greeks, straighteneed up by the Romans, etc. ... it's as if he thinks he's lecturing on the radio, rather than writing a book. Illustrations are our friend! I'm shocked they weren't included.
After dispensing with a given letter's history, he moves on to a random topic inspired by the the letter, e.g. he might have talked about bananas for B, say. To be fair, he kinda sorta tries to keep his 26 essays about words/language/codes, etc., rather than fruit, but there's no real connection other than that, no emotional throughline, and I'm unlikely to remember any of his given anecdotes. Ultimately, this was bathroom reading. So I moved it there, and now I'm finished.
Another reader mentioned Shady Characters, so I'll also mention it, as I also read it, liked it, and it lives up to its promise.
(Note: 5 stars = amazing, wonderful, 4 = very good book, 3 = decent read, 2 = disappointing, 1 = awful, just awful. I'm fairly good at picking for myself so end up with a lot of 4s).