Having an MCU with the 32-bit ARM Cortex M0+ core makes the unit much more powerful than an Arduino having the 8-bit ATmega328 MCU. The more powerful Arduino Zero should be good for complex robotics projects and will likely be a great introduction to 32-bit programming. (The MCU on the Zero also happens to be a very close relative of the microprocessor used in the Canary Instruments energy monitor...)
At the first Humboldt microcontrollers group meeting on May 15th, it was explained to me that one of the drawbacks of the Arduino platform is that it can be challenging to debug programming problems. The Arduino Zero has an embedded debugging system called EDBG. If interested in the details, check out Atmel's PDF for EDBG. The more advanced people in the Humboldt microcontrollers group may want to consider getting a Zero to see whether the EDBG system addresses most of the issues related to debugging Arduino programs.