It doesn't say so on the cover but this is pretty much a history of, or story of BMW motorcycles. The difference is that it is told in a more relaxed manner than most. Still broadly covering the model ranges through the years.
Although paperback, the quality of paper and print is excellent along with decent photographs of the machines. It doesn't tend to go into technical specifications and is more of a story or narrative and as such is worth having alongside other books which, while all essentially providing historical context, do it in a different way. The photos are shot differently too. Again, in more relaxed fashion.
As a general and enjoyable relaxed narrative I'd say 5 stars, but as some may find the lack of specification detail a dissapointment 4 stars is probably a fair appraisal.