Who is this tutorial for?
This tutorial will not go into depth about basic programming practices. It will only briefly explain the principles of object-oriented programming, instead focusing on how Vala applies the concepts. As such it will be helpful if you have experience of a variety of programming languages already, although in-depth knowledge of any particular one is not required.
Vala shares a lot of syntax with C#, but I will try to avoid describing features in terms of their similarity or differences with either C# or Java, with the aim of making the tutorial more accessible.
What will be useful is a reasonable understanding of C. Whilst this isn't needed for understanding Vala per se, it is important to realise that Vala programs are executed as C, and will often interact with C libraries. Knowledge of C will certainly make a deeper understanding of Vala far easier to come by.