This is an extremely solid, nicely readable, book that takes you, with a very practical eye, to about a CCNP level of routing and switching.
I say "practical" because if you're looking fir certs, this is not the book for you. It's for people doing the hands on work.
One caveat might be that a bit too much time might be spent on some routing protocols that are pretty obsolete (RIP for example), but you can skim that stuff with no real problem.
As others have mentioned, the book closes with some truly valuable information about how techs can get by a little better in a business environment. Normally I have stuff like that, but this is trying insightful and has really helped me.