This is a work of propaganda. It's a story about choosing smarts over happiness. Except if I give the pencil a push: then it's a story about choosing happiness over smarts.
The premise is much the same as his "Down and Out in the Magic Kingdom"; a few years into the future, in which interesting social systems have grown up around some of today's fashionable technologies, the main character's down on his luck, and most of the book is spent explaining how he got that way. This time Doctorow tackles instant messaging and music sharing (among various others) rather than webs of trust and Disneyphilia.
The storyline doesn't really require the near-future setting, which works well: Doctorow gets to demonstrate how people would live with his new technologies from day to day rather than spending time explaining them. The only character that's really fleshed out is the narrator, but watching him balance on the edge of craziness is sufficiently entertaining that it's not really a problem — and, after all, it's a short book.
I thought it felt a bit more polished than "Down and Out" did — I enjoyed both books, but this one seemed to have fewer oblique references to currently-trendy culture, so I found myself cringing less frequently. I suspect that this book won't age terribly well, but it'll be interesting to look back in ten years and see which of Doctorow's predictions actually did pan out.
Strongly recommended — and given it's available for free, you can always read the online version and buy the book if you decide you like it.