Why is the Flexis controller one of the best microcontrollers for education and embedded applications?

Low cost.
From $0.37 for an 8-bit MC9RS08KA1
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC9RS08KA1CSC-ND

to $2.28 for a 32-bit MCF51JM32VLD including a native USB port.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MCF51JM32VLD-ND
Low power and high speed.
Pin to pin compatible is the industry first. Both 8-bit and 32-bit MCUs share the same pinouts, so a switching between an 8-bit MCU and a 32-bit MCU does not require a PCB re-design.
Great 68000 architecture, powerful and easy to understand instruction set for education. Its predecessors, like 6800, 68HC11, 68000 and 68HC12 were the most popular microcontrollers in university classrooms.
Large on-chip resources, a great amount of I/Os, up to 4K RAM. 128K flash memory for the 8-bit, and 16K RAM , 256K flash memory for the 32-bit.
12-bit ADC, SPI, UART, CAN and PWM outputs
On-chip USB port for making projects as USB devices
Free CodeWarrior C complier and source-level and a step-by-step debugger
Supported by Jim Donelson's Flexisframework
Supported by Richard Testardi's "StickOS" with an interactive debugger
Supported by Code Sorcery tool chain (compiler, assembler and linker), 100% GPL.
A gateway to more advanced Coldfire V2-V4, ARM microcontroller families
Lowest cost debugger hardware USBDM available at $16 for source-level and step-by-step debugging, a fraction of the price of similar devices from other chip makers.