As venkatesh wrote this is not the right place to ask this question. So tag this question to conservation or conservation biology. I am completely unsure how to answer such a complicated question. Ok, coming to your question Project tiger was first initiated during the time of Indira Gandhi during the early part of 1970's and this is still continuing. First tiger reserves were declared and then recently a project was done by WII, dehradun with numerous researchers now it is taken up by NTCA. One thing for sure the tiger project has increased the habitat of tiger. Camera traps have revealed the new areas of presence and diminishing numbers. So the answer is very complicated habitat quality increased, prey species increased but tiger numbers decreased. this is one aspect of conservation. But this has also increased the public awareness.
There is another problem, that the people who do research in this field (not only tigers but any animal) find it very difficult to get permission to work in the protected areas due to the apathy of the different persons in the forest department (not all but some make it a hell of a job). In the mean time the locals get in and get out of the forest with/without their knowledge. this is another problem which has to be sorted out before any conservation process becomes successful. So in my view none can say if PT became successful or unsuccessful.
In short "Project Tiger" is a conservation success story which involved active participation from the then Indian Government, managers, and scientific community. Initiation of this project has stalled the severe decline of tiger population in India up to a great extent. After the first two decades of success, in the early 1990s, the tiger population of India fall prey to the commercial demand for tiger skin and body parts. Many of the tiger bearing forests lost their tiger population due to inadequate law enforcement and weak management system. After the blow, Project Tiger directorate strengthen the law enforcement, and till 2004 Project Tiger retained its integrity. In 2004-05 after the Sariska disaster (tiger population went locally extinct from Sariska) "Project Tiger" got a functional revolution, and National Tiger Conservation Authority (NTCA) was formed (2006). Right now NTCA is the handling all tiger related work in India.
You can find details on their website: http://projecttiger.nic.in/
And please go through this report: '
Joining the Dots - The report of the Tiger Task Force' (also available on the website)