I've spent the last few months researching and prototyping my own point and click adventure system.
Along with that I've been creating my own camera, dialogue, and inventory system. I've basically thrown it all out and have fully embraced Adventure Creator.
This is probably the best system that I've downloaded for Unity. It's well put together, it keeps the content creator/designer in mind, the source code is clean and concise, and the developer is very, very engaged with the customers.
I couldn't recommend this one any higher. Very well done!