Having a great deal of experience in economics teaching and economic research, I have to say that Varians book is best of all introductive work on microeconomics. The reason is, if you want to fully understand microeconomic thinking, it is not important, at first, so solve equations and to find some optima. More important is to understand the underlying ideas of economic models and to understand how these ideas are outlined and constructed without any calculus. The latter is a matter of writing papers in journals like AER. And even the best papers written are of a more simple style. Thus, Varians book is the best to understand these ideas as early as possible.