What's striking is the use of uber in the title, of course: The German prefix über is wildly productive and Übermacht [over+power] 'superiority, superior strength' is bound to be in any reasonably good German dictionary. And uber has been famously loaned into English, according to some originally from the Dead Kennedy's very fine "California über alles".
What's jarring here is that the American term is more or less exclusively youth language, emphatically informal. It's a tad too much like Kant having written a book called Yo, Critique of Pure Reason, Man. In German, Power (feminine, like essentially all German nouns meaning 'power') is an established loanword (with some difference in meaning), and Überpower shows up on various German websites, including ueberpower.de, an automative performance parts dealer.
In fact, the German translation (it looks like he wrote it into English, then had it translated into German, but that's a guess), is called Hypermacht. A review by Friedrich Mielke in the Süddeutsche Zeitung has high praise for the book, but says:
Die Titel der englischen und deutschen Ausgabe sind unglücklich gewählt. Das Wort „Überpower” gibt es im Englischen nicht. Und „Denglish” oder „Germlish” passt nicht zu Joffe. (rough and dirty translation: The titles of the English and German editions are ill-chosen. Uberpower doesn't exist in English. And Germlish isn't Joffe's style.)The point is hardly about language mixing -- uber and power are both securely established morphemes in both languages by now -- but at the least about what Germans call Stilbruch, 'stylistic incongruity' and ultimately about accuracy of meaning.