Not that it was a surprise, but above is a short overview of Buhari's (APP) victory over the incumbent Jonathan (PCP). Even though Buhari used to rule when he was a military leader this is the first defeat for the PCP party since the military gave up power with the new constitution in 1999.
Here is a great Economist article on the subject which also includes graphics on GDP, where the Muslim population lives, Boko Haram, etc.
The video below from the Economist argues that the election has moved Nigeria to a more liberal system, but remind us Buhari was repressive the last time he was in power.