One might easily assume that any film with a cast that includes Michael Fassbender, Marion Cotillard, Jeremy Irons, Brendan Gleeson, Charlotte Rampling, and Michael K. Williams must be worth seeing. But as the old adage goes, you should never assume. The critical piece of information I left out is that this movie is based on a video game, and that never turns out well, no matter how much talent is involved. Assassin's Creed is a stylized, action-heavy mess, jam packed with so much exposition that I was lost from the start and never caught up to any semblance of a story worth following.
Who is this movie for? If you're a big fan of the video game, you might enjoy it. Otherwise I would skip it and see almost anything else instead.