MVVM: Should a VM object expose an M object directly, or only through getters delegating to M's getters?

Question

the best way to explain is with example so:

this is the model

public class Person 
{
    public int age;
    public string name;
}

Answer 1

Having a ViewModel for any Model could be worse than that. What if you have a hierarchical structure of a Model, or even a simple collection? In that case you'll have to iterate through all models and build a ViewModel instance per-model, and also to register notify-change events or other events. IMHO, this is completely insane, and unreasonable. As DaniCE said, you’ll end up with lot of code and a big headache.