The classical ball and spoke models are cheap, simple to use, buy just not good enough to show a dynamic process involving formation and destruction of chemical bonds. However, those models are excellent for conformational analysis. Also, they tend to exagerate the relation between bond lengths and atomis sizes: it is a good idea to also use Van der Waals models, at least for some representative molecules.
In order to understand a reaction process, it is better, IMHO, to use CG animated graphics, and to switch between several types of models during the classes.
Do we know really the true figure of an atom, or of a molecule?
If there are molecular rotatations or molecular viblations, the ball and spoke model says nothing about them.
Further, the modern physics teachs us that the electrons are spreading around the nuclei vaguely.
And futhermore, the nuclei are suffering from thermal agitations.
The ball and spoke model is weak in these points as an educationl tool.
And the most interesting thing that the students must feel attraction may be the intra molecular mechanism when the molecule reacts with another molecule. At the time the reaction occurs, there may be rearrangement and transfer of nuclei and electrons within and between the reactants. But why do they rearrange in such away? The young students must come to inquire the reason why? They must want to know the key to resolve the riddle of chemical transformation of the molecules that participated that reaction.
How should we teach youngs the above various facets?