It has some useful information for basic repairs... not so heavy on the maintenance side but there is some in there. The pictures and drawings are in black and white, but mostly visible. Only a few are difficult to see. However, they are in 2-dimensions and they don't show you HOW to do the thing, they only show you the general area and the part you want to manipulate. The phrasing in the instructions can be hard to follow without a good visual reference unless you're already a master bike mechanic (which you aren't if you're thinking about buying this). So, buy this for general reference and rely on Youtube for video. The two together are better than either one alone.
Every person who considers themselves a cycling enthusiast should know how to do at least some basic bike repairs. This is not just to satisfy an unwritten standard of being a bikehead, but because it has a lot of practical implications as well. It can make the difference between dealing with a minor issue quickly on your own or waiting a couple of days for a busy mechanic to squeeze you in. Moreover, in the long run, doing the dirty work yourself will save you a lot of money.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.