No matter what performance metrics you take or how many reports you produce to show that your MTTR, MTBF (mean time to repair and mean time between failures) and other process measurements are improving, the value of your service can only be judged by the people who are at the receiving end...your customers and end-users.
If you measure nothing else, make sure you understand just how satisfied your customers are with your services, where their points of pain are and ensure that you do something to minimise that pain.
Do you know the difference between your customers and your end-users? It can be easy to confuse them - put very simply your customers are the people who buy your products, users are the people who use these products. As the person who pays the bill, the customer is the one you need to satisfy, but remember that they will be influenced greatly by the opinion of the end-user, so neglect their views at your peril! Just be mindful that they will be judging the service on different factors - your customers need to see value for money, your users probably don't know or care about the cost of the service, they just want to use something that does the job and makes them feel good in some way. An unhappy user is likely to become the squeaky wheel that irritates your customer and makes them unhappy with the service.
I can hear you saying "we're OK, our toolset sends out customer satisfaction surveys every time we close a call". I have bad news for you, that is just not enough. You have to get out and get face-to-face with your customers and users, even better, go and walk a mile in their shoes! Get out into the business and have a go at really using the services, not just testing them to see if they work technically. See how user-friendly they are, how do they really perform at peak times when everyone is trying to get transactions through. Listen to the buzz from people trying to do their jobs...are your services helping them or frustrating them? Even if you cannot fix their issues, understanding them will help you to provide a better level of service.
Working in IT we are apt to hide behind emails and surveys, even now I find myself clicking on that "compose email" button when I know I should pick up the phone and make that personal contact....I can probably get all the answers I need in 2-3 minutes on the phone rather than via a dozen emails backwards and forwards.
What do you actually do with your survey results? Do you even look at them? I know I have been onsite at a couple of different companies where I have asked to see their customer satisfaction survey results and nobody actually knew where to find them! Asking the questions is not good enough, you have to examine the answers and act on them, and do that in a timely manner.
Review your survey results regularly - daily if you can. Treat a negative survey result as an incident that needs to be resolved, something went wrong...try to ascertain just what that was and prevent it happening again.
Funny thing is, while I was writing this last paragraph I just flicked over to Twitter and saw this from an obviously frustrated service user - "Dear IT, I know you have to send me a'satisfaction survey' after every single query, but I'll be 'satisfied' when I get lost contacts BACK" - that is exactly what I am talking about, this user is not happy, the survey is not helping! Just hope someone from her IT department caught sight of that tweet and did something about it!
Foster a culture of respect within the IT organisation, it is not appropriate to make fun of your customers and users behind the closed doors of the IT department - yes I know it can be good for a laugh, and I have been guilty of that on more than one occasion (not in recent years, I hasten to add) - it is very hard to go out and treat your customers with the respect they deserve if you have been calling them names and laughing at their expense five minutes earlier!
Your customer relationships are, potentially, your biggest asset...make sure they are not your Achilles Heel. If you upset too many customers and don't make it right as quickly as possible, you will either be dumped, if you are an external IT provider or, if you are providing an internal IT service, outsourced.
So, in short, respect your customers, talk to them, really try to understand where they are coming from, respond to their concerns and try walking a mile in their shoes. These are the people who judge the value of your service, their satisfaction is really the only metric that matters...every other measurement only serves to give you information that you can use to help improve their satisfaction with your services.