I'm on my gap year at the moment. It was planned as I felt pretty burnt out after A levels and figured that my attitude towards MORE essays after I'd just finished a bunch of them would be pretty negative and I don't want to compromise my uni experience. In actual fact I managed to get a job at my local uni and have been working there since September. It's not only earned me GOOD money (which I'm now half saving for uni, and half spending on a month in South Africa), but it's made me sit up and realise I don't want to working in an office my entire life.
Also, I've matured a lot as I've been spending time with people at work who are much older than myself, and have a pretty large amount of responsibility to get my work done as it affects the students ect. A lot of the academic staff I spoke to say that they can see a HUGE difference in those students who have come straight from school, who are often (not always, but a lot of the time) the ones who don't take the course seriously, think they're just there for a bit of a piss up and never just pitch in and do the work. They've still got a "school" attitude to education and think everything is going to be handed to them on a plate, whereas uni is a different story, and if you don't put in the work, you're not going to be getting much out of it. They said there's a larger amount of passion for learning and sense of responsibility (to themselves and their own education) from those students who have taken gap years.
Either way, it's not always been a walk in the park, as doing a job all day that you don't really like can get you down, but I know in retrospect, both financially and mentally it will be worth it.
Plus, I've saved up money to be part of an experience that I'd never thought I'd be able to do. There's such a sense of acheivement being able to pay for that first BIG thing, all by yourself with the money you've earned.
If anything, I think gap years should be looked upon favourably. Depends what you make of it though I spose. If you work hard and get the experience, it'll be worth it.