How common is it to get one very positive and one very negative review?
From my experience this is the norm, not the exception. I may sound a bit negative here, but I think many areas of academic research are getting more cross-functional and collaborative; especially in science, and especially in my field (genomics and computational biology). 

Can any one person really comprehend every detail of the work? No! Are reviewers magical people that know everything and recognize novel work at first glance? No! Good reviewers will do their homework, check for related works, or ask their colleagues. But reviewers are also human, and it's intellectually easier to say "this is not interesting/important" as opposed to making an effort to understand the context and impact. Reviewers are human, busy people, uncompensated, and not necessarily up to speed on the latest topics. The peer reviewer may have been a poor choice by the journal or head editor. Peer review is, in my opinion, an outdated idea in an era when the scientific enterprise is becoming increasingly complex. 

But that said it is not always true. If the negative reviewer did leave some constructive feedback, do address it or take it to heart.