Hard to answer without sounding totally arrogant. I consider myself to be very intelligent but I can't prove that to you through this medium but I will try to explain why I personally feel I'm above average within my own little world.
I'm holding a pretty high reputation in my career at the moment and have done so now for a few years. I know that they do not want to lose me and as arrogant as it sounds, I know that they know I'm the smartest guy in the office. I swear I'm a nice guy and feel bad for thinking this because in reality I'm not big headed.
I'm a network engineer/IT guy and have been for 9 years. I know what you're thinking. You have to be smart but you don't have to be a genius. To be honest you can be a total sap and still succeed in this field. I know this because I have worked with one and all he did was Google everything and forget everything.
We all use Google in our day to days but what separates myself from the others is the ability to recall problems from experience during triage and then apply some intuition to figure out what is going on behind a problem you've never seen before. All in a few seconds. I have this gut feeling and my brain does this weird thing that I haven't figured out yet but somehow I just know and sure enough nine out of ten times I'm on the money.
This level of mental ability has many pros and cons for me.
The Pros? I can turn around problems at a ridiculous rate. The staff love me and shower me with gifts during the holidays, I get chocolates, sweets, cards etc. I get invited out to events/dinners. I get to help the staff with their personal machines and get money for doing so. I've won two awards (in-house award system). I have had two pay rises and also managed the IT during a time of transition when my boss left unexpectedly. I was actually asked to run it full time but declined due to lack of confidence (I deal with anxiety & OCD).
The Cons?
A middle ground exists between not being busy enough and being too busy. I've never seen it. I either finish all of my work and twiddle my thumbs at my desk for days and that gets old really fast. Or I get absolutely snowed under because I'm the go to guy. It's usually the latter. Some of my team members will re-direct their own calls to me because they know how efficient I am. This breeds laziness in our office. People know I will sort it out and when I decline to do so, things get ugly. We have arguments and it makes the atmosphere very uncomfortable.
The other con is that the others get annoyed at themselves. Once one of my colleagues walked out for a while after struggling with an issue he'd been on for two days. I thought I could help him, strolled over and fixed it in a few clicks. He flipped out at me and walked off. This leads nicely into my next con.
Sometimes I get tunnel vision. What do you do when someone requests software to run in an environment it wasn't designed for? I'm too nice so I'll tell them "Sure, we can give it a go." and subsequently spend the next three months pulling my hair out trying to get it to work properly. There are problems that I struggle to solve and the people in my office forget that. I get transfixed though, like a detective working on a favoured case. I can't drop the issue it's like I need the solution. I stress myself out something awful with this. Usually I don't let up and it gets in the way of all the other jobs nicely building up from my colleagues. Eventually I'll get the solution and it will be crazy like, writing a script that replaces a .dll every two minutes but only if a certain file exists and was created on a certain date etc...
The final con and the con I have been struggling with of late...
I'm depressed. I'm depressed because I'm bored and I'm stuck in this fucking job. I don't get paid enough and I've seen it all. I have a degree in animation and games design. I create maps for the Source engine and write my own games in my spare time (I'm also writing a novel) and I'm stuck in IT. It doesn't stimulate me creatively at all. "Why don't you leave?" I hear you say. This place will not let me go easily. I already mentioned I might be looking to jump ship and they begged me to stay. It's not just that though. All the jobs I could have are in IT. I'm not passionate about IT but there are no games design jobs around this area (around London) I can't move abroad, not with my wife and two kids it would be unfair to drag them away, so I'm stuffed.
I look every day and pray for another more creative role but until then I'm stuck here. You ask what does it feel like? Not nice really. I'm not making the money I think I should be and I'm not doing what I live for. I'm an expensive tool that my employer holds dear.
It felt so good to get that off of my chest, thank you for giving me the opportunity to do so.