This "ultimate power" and a few other small details in the story (trained rats?) made me think that this series may have an underlying supernatural thing to it, which is hard for me to describe because it did not go into too many details about the "ultimate power" yet... this is definitely an intro type of book, but do not be mistaken, there are no boring details here - every single moment is to be accounted for.
My only issue is that every single female character, other than Sarah Jane, were deeply flawed and unrelatable. Her mother, though loving and loyal, was secretive and seemed absent a lot. Her female classmates and friends were either gossips or bullies, and even her aunt was mean, controlling and vindictive. And although the male characters had their flaws too, they were more supportive and caring towards Sarah Jane. (The love between her and her little brother is heartwarming and adorable.) Which is wonderful to see. But I felt like it wasn't enough... it might just be me being a bit sensitive to how these female characters were portrayed.
However, I really did enjoy the typical aspects of the story where the mafia is involved - the typical stereotyped characters and their and names, quite humorous and fun. Yes, the whole book has a Bourne Identity meets the Sopranos vibe to it, but it is definitely the young adult version of it. The fight scenes and action are there, but not so extreme.
The ending just about killed me, but I couldn't see it ending in any other way! It's definitely a cliffhanger - not one that I expected at all! And it was such a good one too! One that you'll definitely appreciate and will keep you biting off your fingernails until the next book!