Is Technic compatible with Mindstorms?
Yes.

The current Mindstorms sets are completely Technic orientated and use the Technic pins (i.e. [part:3673:7]) to connect to the newer Technic Beams (i.e. [part:32316:7]) as well as the original Technic Bricks (i.e. [part:3894:7])

The various different size pins and axles are the way to interchange between these.