As far as I know the note is quite accurate. Sad, but true. In order to open certain cecst, you need to run an an app or something like that. At least that's what some let's Players said on their reviews. And you can buy certain weapons with REAL Money which is... not my thing. I mean after spending from 50-80$ on the game, I don't want to spend any more money just to get 100% out of the game...

Thank you all for your comments on this! Right now my computer is far from being able to play AC:Unity... It's not up to the "Next-Gen-Games" at all. So I'll probably try out Black Flag first (perhaps there'll be a special offer on steam. Who knows?) and Rogue. But first, I have to complete AC:III.