I don't think of Song of Scarabaeus as a *memorable* book, per say, but it is definitely a very, very enjoyable one. I zipped through it in less than 24 hours, and just couldn't put it down. It had action, suspense, and romance, and never seemed to suffer from any slow or dragging moments.
Essentially, Song of Scarabaeus is great sci-fi/young adult/romance fare, and it reminded me at times of the universe from the video game Mass Effect (which I love), as well as from the TV show Firefly (which I also love).
Edie (the protagonist) is a character you can root for, a character with a strong moral center but also the desire for freedom. As for Finn (the other lead), I felt that he really grew as a character by the end of the story, and enjoyed going on that journey of development with him. The secondary characters weren't as strong, though, and perhaps with the exception of Cat, were much more one-dimensional.
As for the romance aspect, it was just the kind I like in a sci-fi or fantasy book, in that it exists, but it's not the main focus. The book doesn't really go into depth on how the two lead characters (Edie and Finn) *feel* about each other. Rather, you, as the reader, infer a lot based on their words, actions, and concerns (and, in Edie's case, thoughts, since the book is told through her POV). Don't get me wrong, the connection between Edie and Finn is a major part of the story, but while the bond between the two characters is highlighted, I like that it doesn't shove the characters' emotions in your face. Also, this book is mostly about the build-up, so don't expect anything too steamy.
All in all, this was a great book - a very fun and exciting read. Everything was done well, and I will definitely read the sequel soon. But, I don't think there's anything particularly deep or remarkable about Song of Scarabaeus so that, five years down the line, I'll think of this book, or be dying to re-read it.