Do not get the impression I have a language bias. I am a language agnostic. The reason I like python for beginners is that, in a fairly short period of time, the students can see that computing can help them to accomplish real work and enable them to do significant tasks. It seems to be that this language is in the "Goldilocks sweet spot;" i.e. that the level of abstraction is "just right." Python is an effective tool for engaging the students' enthusiasm and interest. At this early stage of the ballgame, this is very important. If you frustrate your students with excessive abstraction or with operating at a very low level at an early stage, they don't go on and they don't develop, and they choose other fields.
It is a deliberate decision of our program for students to be exposed to more than one language. Our introductory course teaches procedural programming using Python. This is the first third of the year. The other two thirds focus on event-driven application development and on object-oriented data structures. We like for our students in each class to write a nontrivial application that applies the concepts they learned in the class. The switch from Python to Java shows the students early-on that different languages have different architectures, but that they do many of the same things. We place a strong emphasis on our students being able to read documentation and on being able to apply it to solve some problems they are working on. We are not producing "API Monkeys," but resourceful people who know how to scrabble out the solution to a problem. We develop the attitude of "use wheels, don't reinvent them." However, it is sometimes necessary to invent a new technique to solve a problem; our students learn to be resourceful and handle those situations as well. As we all know, there is no neat connection between existing code-bases and the new things we wish to accomplish.
In our second-year classes, we often program in C. By the time the students are to this level, this experience is meaningful and not frustrating. Our approach has bene successful. We have a program that is growing and we sending an increasing number of students off to the university who major in computer science, computer engineering, and related fields. Many of our students do co-op experiences at local companies, and their experience has been good. The are clever enough to be doing real work pretty quickly.