Maybe the technical aspects of the book are okay.

However, the big problem with legacy code is always political. And the only book I've seen ever try to address that is "Kill It with Fire".

It's one of the few books that talks about the need to keep your team motivated and plugged into the political system given that they are working on the thing that's super important but also almost invisible. You need to be constantly selling what is going on in front of the important eyeballs.

Unfortunately, a lot of the anecdotes have an undercurrent of "Until the system has actively exploded into a million pieces such that somebody with real power has their ass on the line, don't bother."