1. Graphics
On this point I have to say that the games do not take much. Assassins Creed 2 is detailed and Faithful, it may be Assassins Creed (1) be seen easily with the overall graphic. Overall, one can say that both games are almost equally well here.
2. Control
If you came clear with the control of AC2, you will have no problems here, because it is almost the same.
3. Sound
Here Assassins Creed 2 has ahead: Both the sound as well as the voices / conversations. In talks it sounds at AC (1) sometimes as if it had been recorded with the phone. If it was so intended, I think it's not a good idea.
4. Gameplay
In AC2 can be / there are ...
Take swimming, side missions, weapons etc bought with money, watch as the city by day and night looks, to heal injuries only by the help of a physician, historical background information, a quick trip station, puzzles (glyphs), ...
All this can not be the first part (yet). For example, to heal all alone in a fall from a great height - that is my opinion, although good (you do not have to run to the doctor), but not realistic.
But as you can see that from the first halt things have improved for the second part, and so it must be !!!
Of the battles there are hardly any significant differences between the two games. While there are a few more movements in the second part, but that is hardly noticeable.
The missions are varied in AC2 and the story is longer and more immersive than the first part.
CONCLUSION:
Who AC2 liked because of the scenery and graphics, can instantly access here and buy AC (1).
Who but the game due to the aforementioned improvement was thrilled a long season, a gripping story and a good sound will, the game would be better to try once (borrow) before buying.
If you read the review, you might now think that one AC (1) should not buy to prefer. But I have here part 1 and 2 are compared and - it must indeed be - was the second part more excited (it would be bad if there were no improvement).
Nevertheless AC (1) remains a top game that not coincidentally Platinum ("The Best Of Playstation 3") has become.
In my view, AC (1) due to the short season, the diversified low emissions and less intriguing story just a "sequel" before the start of part 2, which is actually from the frame / principle is however the same game !!!!!
So you should play the game once sample / borrow in order to test whether one should buy it.