Below is a list of tasks which you can perform in Assassin's Creed:
1. Save a citizen - Kill a bunch of baddies.
2. Vantage points - Climb up a tower and press triangle.
3. Eavesdrop - Sit on a bench and press triangle.
4. Pick pocket - Follow someone and press circle.
5. Interrogation - Follow someone and punch them three times.
6. Flag collection - Collect a bunch of flags.
and finally 7. Actual assassination's - Walk up to the bad guy and press square.
These 7 tasks make up 90% of the gameplay in Assassin's Creed, the rest is running around and a plethora of unskippable cutscenes.
The game structure is as follows:
Go to one of three strikingly similar cities, listen to some guy witter on in the assasin's bureau, complete a few of the tasks described above, most of which are duplicates (i.e. two eavesdropping missions with what looks like the exact same guy both times), then go off and stab the bad guy, listen to his dying words (all 3000 of them), run back to the assasin's bureau (where the same guy will witter on a bit more), then return home to have your master give you an overly cryptic and melodramatic speech about your role as an assassin. Repeat three times for each city(!) and then enjoy the stupid climax.
As you can probably tell, the game is way too repetitive and eventually becomes boring. Even the people on the street say the same things over and over. You'll often hear a man preaching about god at the top of his lungs, then later you'll here another guy who repeats the exact same dialogue, WORD FOR WORD. It's like the guys at Ubisoft blew the budget on advertising and fuelling their hype machine, Halo 3 styley, then fleshed out the game by copying and pasting gameplay that you can experience in the first hour or so. It's as if the gameplay itself was an afterthought and for that reason, 2 stars is being generous.