The first game, and pretty much every game in the franchise barring Black Flag (and BL only because it didn't start life as an AssCreed game) are rancid shit.
AC1 is little more than a tech demo.
There's no point in having the open world since there is absolutely nothing to do in it. You have 4 or 5 types of side missions, and I'm being generous referring to them as such, of which none are fun to play. The main missions allegedly give you freedom to complete them any way you want, but there's always a very obvious ideal parkour path that brings you near the enemy and lets you stab him from above with the hidden blade.
The combat is awful and the AI braindead, you can just stand surrounded by a dozen enemies and wait for them to come at you one at a time, allowing you to just spam counter to win every battle. You have a variety of tools at your disposal, yet they all boil down to the same.
A dev even went on record saying that the flag collectibles in the game only exist to waste people's time, you get nothing for collecting them.
By that point games like Hitman, Metal Gear, GTA 3/Vice City, DMC3 had been around for a long time. There's no excuse for the game being as shallow and devoid of content as it was.
The story is pure Jewish propaganda - barring a few exceptions the Muslims are portrayed as innocent victims of European/Christian brutality, while the Crusaders and Templars are shown to be completely amoral monsters that inflict pain and death upon civilians for fun.
Then there's the completely schizophrenic monologuing the villains give when you've killed them where they try to justify what they've been doing, despite the fact the game clearly shows you they're irredeemable monsters.
Altair is also a completely unlikeable cunt, as are all the other assassins. Ubisoft, being French faggots, mostly gloss over religion (during the fucking Crusades!), instead option of pushing the gay as fuck muh conspiracy angle, and even then failing by making the "everything is permitted" faction the good guys for whatever fucking reason. Good to know they're such strong supporters of libertarianism, I guess?
Sorry for the rant, but I struggle to understand how this shit franchise ever got as popular as it did. To this day I am mad Black Flag wasn't a standalone IP, instead getting AssCreed grafted on it like a malignant tumor.