Is it possible to wire this motor shield designed for the Arduino up and get it to work for a Raspberry Pi 2?
It's likely that it can. The arduino produces 5V logic levels whereas the RaPi only uses 3V3 so that's the main worry but, the L298 spec (the H bridge device used on the shield) I believe allows TTL high levels of 2V to be used.
OK I've just checked and the high logic level requirements are a minimum level of 2.3 volts so either 3V3 logic levels or 5V logic levels are compatible.
Regards the efficacy of this shield, take a look at the L298 spec or read this question on SE.EE