The expression this.get('myproperty') only works when you are working within a computed property (in that case 'this' points back to the view model itself.
If you want to set the value of a model property from 'outside' call .get() on the model itself (even for nested objects). Eg. this.get('customer.name')
For computed properties you can just call the method directly on your model object. Like this:
varorder = kendo.observable({
OrderNumber: '1234',
Customer: {
Name: 'Joe Blow',
Address: '123 Main Street'
},
getSummary: function() {
return'Order #'+ this.get('OrderNumber') + ' for '+ this.get('Customer.Name');