I loved the level design, the art style, the technology and some of the ideas in Assassin's Creed. But some issues, most which you've complained about, did put me off from even finishing the first game.
AC2 improved AC in every imaginable way, except for visuals on the PC. It borrowed all the good stuff from AC, improved upon the script, the voice acting, the plot and added in one of the best musical scores of this generation. And I look at Brotherhood and Revelations as "Add Ons" to Assassin's Creed 2, which they actually are. I won't be surprised if the next game on the next gen platforoms is called Assassin's Creed 3.
If you haven't spoiled AC2 then I suggest you give it another shot.