Wouldn't say it's the worst, despite its numerable flaws at the moment (AC3 imo is one of the dullest games ever made). Managed to get my hands on it and while i can't get above 30 fps (hardware isn't quite above minimum either+ on laptop, also patched), it's certainly worth playing. I've only seen walkthroughs of Rogue since at first it was exclusive to consoles - the only thing i like about Rogue is that it ties all pieces from AC3 to Unity together, other than that it's just Black Flag 1.2 Black Flag was fun to play around with but fell short of my own expectations, so far i seem to be enjoying what Unity has to offer. What surprised me a bit is that you can no longer carry bodies, pick up other weapons or select the blade itself as "main weapon". Plenty of lags, sudden deaths in Co-ops, but tbh i haven't tried it on proper internet connection. Enjoying the parkour (has some issues, sometimes i'd land through solid objects for no reason :v) and combat system (no more silly kill-streaks).

As a huge fan of the Assassins Creed series i'm pretty disappointed that it came to this, this in no way lives up to the standards of black flag or rogue.

The image you found on Google was taken probably before the patches, haven't come across this kind of atrocity myself (yet).