Problem one is the host of YA tropes in the characters and their relationship to one another. Emma, a card-carrying member of the Bella Swan school of heroines, is exceedingly clumsy: "I'm betting Cinderella didn't feel this foolish, but then again, Cinderella wasn't as clumsy as an intoxicated walrus" (2). Note, too, Banks' sense of humor. This pretty much captures it perfectly. Emma meets Galen, Syrena prince, by tripping and smashing her face into his chest. We are treated to these inner thoughts:
"Tripping is bad enough. Tripping into someone is much worse. But if that someone has a body that could make sculpted statues jealous—and thinks you've broken your nose on one of his pecs—well, that's when tripping runs a distant second to humane euthanasia." (5)
This girl seriously needs to sort out her priorities. Also, she spends way too long thinking about the awkwardness of the situation. While she's thinking, she remains plastered against him, because obviously that's less weird. Everyone trips sometimes. He would laugh and move on if it were the real world. It's not though, so no one's phased by how long she presses her face against his chest on first acquaintance. Here's one more quote to explain my distaste for Emma: "If stupid were a disease, I'd have died of it by now" (119). This attitude is so unhealthy. I encourage girls not to think of themselves this way, even as a joke.
Galen, of course, is drawn to her from first meeting, purportedly because his mermaid (sorry, Syrena) senses are tingling. Meant to be together, blah, blah, blah. They met while she was on vacation (during which time her best friend got eaten by a shark). She goes back to Jersey and he shows up in her school with an identical schedule. When she tries to avoid him after the first class let out, he grabbed her wrist and, when she tries to pull away, he grips harder (41). This is a primo sign of a controlling guy. I was not surprised to learn that he had 'serial-killer eyes' (290). Among his other charming qualities, he also bosses her around constantly and takes advantage of her memory loss to convince her to accompany him somewhere.
I would also like to point out that Emma completely forgets about Chloe's death and that she's supposed to be sad within a day of Galen's showing up at her school. Meanwhile, her mother hears that Emma tripped and hit her head, freaks out and accuses Emma of sleeping with Galen, her boyfriend. The two are not dating and she refuses to believe anything else. He was a transfer; it was his first damn day at that school. WHAT WHAT WHAT?
The other big problem I have is the inconsistency of what the Syrena know about humans. Galen is an ambassador to the humans, which basically means a spy. He is bewildered by: phone books, people having more than one name (first and last), lip gloss, and countries. At the same time, he is capable of using a phone (likely a fancy modern one) and driving a car (note: one with a manual transmission). He was also capable of passing all of the high school classes she was taking. Plausibility fail.
Of Poseidon had some seriously major flaws, as I've pointed out, but it was still a quick and enjoyable read. I suspect many people will enjoy it more than I did.