Inkheart's got a whole lot of metaphors and similes up in it, which makes it pretty fun and lively to read. And in a book where the narrator is pretty matter-of-fact (be sure to read the "Narrator Point of View" section to get the details on this), these similes and metaphors help keep things interesting. It's hard not to chuckle when Fenoglio is described as dancing "around the cramped room like an old bear" (46.24) and his face as "wrinkled like a turtle's" (24.9), which helps keep up engaged in this otherwise pretty dark book.
It isn't like we're swirling in a sea of hidden meaning when we read Inkheart, though, and as a general rule, the style tends to be direct and plain (which fits nicely with the tone). The descriptions are clear, and help us envision what's going on. For example, when Capricorn's men come for Mo, there's no confusion about how Meggie responds:
Meggie began to run. Gravel crunched under her feet as she raced toward the house. The front door stood ajar, there was no light in the entrance hall, but Meggie heard loud voices echoing down the corridor that led to the library. (6.53)
There isn't a simile or metaphor in sight in this passage, and the action—and Meggie's reaction—come through crystal clear.