It is the only project the entire original cast returned to work on.
That alone was enough to make we want to play it.
In addition, I had heard that the writing, story, and voice acting for it was very well done. Almost good enough to be viewed as the 3rd movie that never got made. (Ignoring the 2016 remake)
I wanted to play this when it came out in 2009 but never found the time. Now in 2018, it of course feels a little dated, with the controls on PC being a bit difficult at times. But it has definitely been an enjoyable diversion.