I don't know why people act like the first Assassin's Creed is somehow obsolete. It has:
1) A completely different story.
2) A completely different setting.
3) Altaïr the badass (vs Ezio is the ponce).
4) Better story if you pay attention to it. AC2's story was a contrived cliché-fest focused too much on that muppet Ezio. AC1's story was driven by more subtle sub plots.
5) The best combat of the first 4 games. After the first game, the combat got too smooth and flashy. Although they carried over most of the mocap from the first game, the new moves they added were too fanciful. As I've said many times, despite having less variety, AC1 combat was raw and visceral and puts the rest of the games to shame.
6) Half decent mouse input. I've only tried the first four games, but aside from AC1, they all have appalling mouse acceleration. AC1 still has pixel skipping, but at least it's playable.
I can see why AC1 might pose a problem for the typical COD-playing ADHD gamer of today, but if you've got the patience, it's well worth playing. I've played the whole thing 5 times, and spent countless hours just messing with guards and exploring the holy land. Unfortunately DX10 mode seems to have got broken somewhere since 2012 (stutters - probably something to do with Nvidia's drivers). The game has a horrible post-processing haze effect everywhere but Damascus, but it's no worse than the upper-screen pseudo-HDR effect in Brotherhood, or that horrible glassy/smoky effect in Revelations.
While I can entertain the idea that UT2004 made UT2003 'obsolete', the idea that AC2 made AC1 'obsolete' is thoroughly absurd.