Pyret is inspired from Racket, which starts at step 1 with functional programming. It's not about readability or getting people to learn as fast as possible to write basic code, but to try and teach core program design principles easily and build a solid base within a single semester. The syntax is not as clean as Python, but it offers much more clarity in terms of testing, signatures, and offers a very interesting method of writing loops with map/filter/foldr.

I have a bias here, as I help teach an introductory course using DrRacket, and many of my colleagues are very aware of Pyret, some even helping to develop it. In one semester, however, we have students with a full understanding of recursion, linked lists, many other common data structures, anonymous functions, functions as data, and understanding of map/filter/fold and how to use them. The class is specifically aimed at people who do not have prior programming skills, and works very well in my experience. Yes, it is a lot, but it builds an incredible base, and if taught to build on itself slowly, is actually very minimal conceptually. The optional features in Pyret are probably allowed with that in mind.

One of its weaknesses, arguably, is that it doesn't look like much else out there in common use, since it's a Scheme. This syntax is an attempt to try and make the same ideas translate to other languages easier, such as Python/Java.