If so how long is it & is it worth the money?

Well, I didn't really count the time and I got it free with the PC version.

Interesting enough, though not really that long from what I can recall.

How much does it cost?

$10US

If it isn't that long then I don't seen the need to shell it out.

Yeah, I don't think I would say it is worth that much.

it does come with added extras though if you play MP at least, as it's animus pack 3 aswell as unlocking some of the exclusive chars for that...
Also if your a point/trophy whore it's another set of them to do..

I don't play online & (while I like Achievements & trophies) do not buy content based upon if they are included

I got it free with the PC version too... I don't remember it being anything special and those games are plenty long enough out of the box.

The actual gameplay is about 1-2 hours depending on how skilled you are when I did it I found it worked better the time I played it after completeing the game rather than before.. oh and it gives you a little more about the mysterious william...

oh and if your in the US just watch amazon etc they tend to sell points cards for half the normal price at random points in the year so you might find it worth $5

Really? I have never seen them on there that cheap. It is good to know though (I'll be pissed if they go on sale tomorrow considering that I just bought one for full price on there today lol).