Only Broken Sword game I haven't played is the fourth one, and as I have heard only negative things about it I'm sure it will take me some time for me to do that.
What this game does the best is the respectful apporach to the previous titles, especially 1 & 2. However, in terms of overall continuity it feels a little bit out of touch. It feels like as if it was meant for especially newcomers of the series and for those who want to get some old nostalgic vibes from it.
The playtime was in my opinion acceptable. It took me nine hours to beat the story, allthough I missed a few achievements. About same amount as in the first and the third installations.
The story was as fascinating as one could expect from a Broken Sword-game, with religious mysticism and conspiracy, with some twists and funny references.
All in all, I prefer the first and the third one (I know that this is an unpopular opinion) over this, but I still recommend it to everybody.