Customer Service is easy, right? Figure out how many contacts come in the door, how fast your agents can answer them, staff as needed.
Over the last decade, the notion of over-performing in Customer Service has become the norm: Exceed Customer Expectations (usually meaning that after the customer has a problem, the team follows up NOW, and does everything possible to solve the issue and then some). In this way, you will impress the customer by recovering the situation, and this will engender a greater sense of loyalty toward your product/company. Measure Customer Sat and Net Promoter Scores, and you will be moving toward a long-term virtuous circle.
What if that approach doesn't work?
Thought-provoking post on Barrett Sales Blog, Why you should stop delighting your customers.
Long and short: Put your money into making it easy for your customer to transact business with you, and they will come back for more. (Wish there were some performance numbers in this blog post you could hang an ROI hat on, though.)
In the on-line world, this is easier said than done. That doesn't mean you shouldn't make the effort and question some of the current 'best practices'.