I wouldn't describe the place I work as especially forward-looking, but even we are caught up in the buzz about the mobile web. I am a sceptic. Viewing the web on a mobile is fine ... so long as you don't have access to a bigger screen at the time.
Nevertheless, HTML5 and CSS3 aren't just about the mobile web. The first part of the book - a little less than half - focuses on HTML5. Or just "HTML", as it's called by those who don't want to be oppressed by version control (Hmm - how does that work, actually?). This does quite a good job of explaining the new tags and the repurposing of one or two others, so that they are interpreted with semantic meaning rather than a specific presentation style (although, unless you choose otherwise, any browser will almost certainly render <b> as bold, for example). The new tags around articles, sections, headers and footers all seem quite reasonable; the hype over canvas, audio and video is ... well, rather more hype. There isn't a single standard supported across all browsers for audio or video codecs, so you have to encode in multiple formats and consume twice the disk space (backing off to Flash doesn't give you a single solution either, as Steve decreed that Thou Shalt Not Allow Flash On An iOS Device).
However, there are a handful of fairly serious flaws in the curation and editing of the book. The index is laughable: plainly the print edition (which of course is what I have) simply hasn't been considered in any depth. Likewise, text around some of the illustrations (mainly in the area of canvas) describes changes between different versions of an image as "clearly visible". In fact, in the print edition they look identical. The footnotes and presentation of referenced URLs isn't consistent across chapters and there's at least one reference to a non-existent figure. For the level of knowledge I need about these technologies, the text was adequate, but it may be difficult if I ever need to look anything up in it.