I'm on a quest to play every main-series assassin's creed game, because ? I just beat AC2, and will be deciding whether to get all the Truth glyphs or just move on to Brotherhood tomorrow.
AC1 is pretty decent. It hasn't aged well and it's repetitive, but it's kind of a marvel how stripped down and simple a triple-A game could be back then, compared to nowadays when every big game that comes out is a bloated nightmare with 400 hours of bullshit. A lot of features that are ruin every modern video game are here in prototype form, rhythm game combat, "open world" full of repetitive shitty side tasks, parkour, etc. Still, everything fits together nicely in this one and nothing becomes overbearingly awful the way it will in future games. 3/5 for me, solid game.
AC2 is great. It's just Assassin's Creed but bigger and better. Starting to see the Ubisoft Formula in the way the open world is set up, but the hide in plain sight style stealth is improved, parkour is improved, combat is easy but flashy and satisfying. The main story is decent, Ezio is a better character than Altair who was monotone and boring, and the metanarrative with Abstergo, along with the "Truth" stuff with the Annunaki just continually gets more insane as the series progresses. A lot of people hate that stuff but I love it, it's completely unnecessary to the games being good, extremely self-indulgent, but they just continually double down on it and even in the modern games they're still doing it. The game kind of falls apart in the last act though. Everything past Silvio Barbarigo is terrible, the game massively overstays its welcome. You steal the apple and have a swordfight, and there's an "all my friends are here to help" moment which isn't earned because the enemies don't feel threatening. Then the guys from A Clockwork Orange show up and steal the apple, and you kill them, and then Savonarola shows up and steals the apple, and you kill him after an agonizingly long and un-fun series of mini assassination missions, and the game still keeps going after that, leading up to a climactic fistfight with Rodrigo Borgia, who was a terrifying in literally every scenario except a fist fight.
Up until that point the game was a 5/5 for me, but the last 3 or 4 hours of the game being shitty is too big a flaw to ignore so it drops to a 4. Oops.