Damned boring. The Dragon Book is one of those ones that shows up on everyone's Top \d+ CS/Dev Books list, but it's one of the ones that are there because you're supposed to be impressed with the implication that the list-maker got all the way through it, not because it's genuinely great.
It has all the information you need to write a functioning compiler for almost any kind of language you'd want to write a compiler for,† it just lays that information out in the dullest, most laborious way possible. The fact that this edition uses Java for much of its code doesn't help, but it actually doesn't hurt nearly as much as you might expect; too bad that's only because it's very light on working code samples.
If you somehow make it through the first eight chapters, the last four are more interesting (if more uneven), but not sufficiently so to salvage the whole book.
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† Often missing, however, is a defence of non-obvious design decisions as being genuinely good ideas rather than just accidents of history.