Raspberry Pi has written a blog post on the new Mu, saying:
Mu is intended to be not the only Python IDE you’ll ever need, but the first one — the editor that helps you start your coding journey, but not necessarily the one you finish it with. So when you’re ready, you will have the skills and confidence to move on to using a more advanced Python IDE.
You can use Mu in a number of modes; modes make working with Mu easier by only presenting the options most relevant to what you’re using Mu for:
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.