> If you know C, you will love Arduino.
Isn't it the opposite? If you aren't comfortable with C, Arduino has a simple enough API and good enough tutorials+documentation that you can still make it work.
If you are comfortable with C, just about everything is better than arduino because you'll get debugger support and full control over all the goodies like clocks, charge pumps, DMA controllers, asynchronous ADC operation, pin multiplexers, USB/Ethernet controllers, etc.