Depends on platform - on PS4, its just too poor performance to be worth buying with so many other games worth your money (eg shadow of mordor. and if you want AC4, its a better game and looks stunning on PS4)
On xbox one the framerate is at least good enough to be playable without pissing you off since its a 25-30% kind of boost.
Presumably a good PC also runs it at a good framerate.
The thing is that the Xbox One "having better performance" is something that is now been thrown around, after the Digital Foundry article. Before that, many assumed the XO version had problems because of the videos and streams.
Heck, a few including myself with the PS4 version haven't experienced any problems.
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But, that's the "magic" of the AC games since the first one. It doesn't excuse them, it doesn't mean the problems aren't there; on the contrary. But glitches, bug and many other problems has been common for this franchise since day one (especially I, II and III...even the Vita game). Yet, after all this years; now is the time to ignore the game until it's fixed because of the many problems (especially at launch)?
Assassin's Creed has always been a series with a "YMMV" (your mileage may vary) as a hidden subtitle. This new one is a bug/glitch-ridden as a good chunk of the previous ones. Again, it doesn't excuse the problems or Ubisoft as a publisher and developer, but anyone that played at least ACII without worries of it's problems (of which there are tons of compilation videos and screenshots); shouldn't start to be worried now just because of the more vocal outcry.
Of course, people should be better by waiting until either more patches and/or lower prices (or rental, or used copies) if they chose to. But that still won't guarantee that by then, the problems won't be there on your end. Even when many will say "it's fixed". [Ex: After like 6 months (around July this year) I got Battlefield 4 and still got my save erased a few times and constant disconnects, yet most agree that the main problems were fixed.]
But on that same PS4, I've played around 12 hours of Unity, with nothing even close to the videos of the single digits framerate at the church. "YMMV"!!!
Of course, it would be nice if Digital Foundry analyzed fully installed digital versions of this. It might explain the lack of problems of some, and maybe the better performance later of others.
EDIT:
Darn, this was way longer than my phone led me.