Sure, Assassin's Creed on the PC is a port from the consoles - some design decisions and UI elements are unavoidably "non-PC style", but otherwise Ubisoft is to be commended for a solid conversion. The underlying game itself still suffers from some fundamental gameplay issues. The game just gets repetitive towards the end, with most of the difficulty coming from the ridiculous odds you constantly end up fighting against. The whole idea of a stealthy assassin going about doing his dirty deeds unnoticed gets thrown overboard in the later parts, and the open melee combat, while visually nice, just isn't very compelling.
In a way, Assassin's Creed on the consoles was a flawed gem, and the PC version, while being technologically a very competent and fairly polished conversion, is just as mixed bag - great, yet deeply flawed in the gameplay department. The engine is very impressive, and technologically the game surpasses the contemporary competition, yet it fails to really grip you with enough unique gameplay content to keep the interest going. The storyline partially saves the day, giving some incentive to keep slogging onwards, but in the end Assassin's Creed is only "good", not "great".