MacBook Pro 13in Late 2012 v.s. MacBook 12in Early 2015
According to the specifications you have given, you most likely have a i7 3520M on your MBP and a Core M 5Y71 on the MacBook. If you compare the benchmarks done on the CPUs, you'll see that the i7 excels both on CPU as well as the GPU benchmarks.

Your current MBP is more powerful than the Core M MacBook that you are considering. It will be kind of a downgrade if you purchase it. Wait until WWDC 2016 to see if Apple upgrades it MacBook product line.