From the perspective offered by such a theoretical background, further research is easier to achieve, without having to redo the research with data already available. Another advantage for using typologies is the fact that they are a useful background for analysis not in the sense of being used as tools, as mentioned before, but as actual sources of practical information. For instance, the term democracy is used by Plato in a particular sense, while by Aristotle in a different way. However, such differences represent a basis for analysis and information. They were useful for studies in the medieval world and for the development of analysis in the next centuries.

The major disadvantage is the...

They are not extensible from the point-of-view of their author. In this sense, the democracy as described by Plato is a reference point in the study of democracy in general, but it offers a strict perspective, an element which may hinder the analysis process.
Overall it is fair to say that typologies are important for the study of comparative politics, having in mind both advantages and disadvantages they offer.

Reference

Goodin, Robert E., Hans-Dieter Klingeman. "Political Science: The Discipline" in Robert E. Goodin, Hans-Dieter Klingemann (Eds.). A New Handbook of Political Science. London: Oxford University Press, 2000.