I played this game on Xbox 360 and loved the concept of the game and to be honest I don't recognise any differences between the base game on console and this supposed "Director's Cut". So don't go in expecting an extended experience as I did. The story is quite fascinating and that's what kept me playing, although the missions lack some variation. This is a common critique, but given that this was the first entry of a new IP, I understand they had a more limited budget (~$20million). However, excessive grind is a common feature even in recent AC entries, so to give AC1 a bad repuation for it seems unfair to me. For me, the limited sandbox is a bigger issue; there's not much freedom to execute your assassinations. Additionally, a certain class of NPC has a very limited dialogue library, so be prepared for some greatest hits to be featured multiple times. I also find the controls quite clunky, although that may be due to my own skills, or lack therof. Regardless, I find movement much smoother in more recent entries.
If you have never played AC1, I won't spoil the story for you, but you get a game which I played through in 12 hours. The play time can be extended if you don't ignore the plethora of collectibles. I recommend you leave these alone at first and purely focus on the story. You don't really get anything extra for finding them all, except for a sense of pride and accoplishment. Oh wait, wrong company. But seriously, don't bother with all the flags and stuff that are "hidden" in the game, because you'll lose interest very soon. I adopted both playstyles, so take my word for it.
Anyhow, the game's very affordable during the many sales and if you buy on GOG you don't have to worry about DRM. Now, the description on GOG Galaxy mentions that the game is non-linear, which is quite a stretch. Occasionally you can choose which mission you'll do first, but in the end the order doesn't really matter. I suppose this comes back to my point about the limited sandbox.
