I've been in a leadership position, starting with HoD, for the last 15 years of my career. It got me my first Chair, and various pay rises and promotions. It's also bloody hard work.
Things to think about: are you in a position to bargain for a promotion? If you're not already at Professor level you need to talk to your Dean/Head of School about prospects.
The team and their attitude to "academic leadership". As someone notes upthread In my experience (not as HOD), humanities have staff who question, defy, present opposing views, by nature - or at least, because that's what they do in their discipline Yes yes yes.
My 1st experience of being HoD was in a department which (unbeknownst to me) had a bit of a history of conflict between its HoD & its professor. Generally, HoDs were at SL, and the professor only took on HoD with reluctance. I walked into that - I'd just been appointed so didn't really know the history. Then we got a new Prof - famous international feminist with whom I thought I got on well. Until I started working as HoD. She basically conducted low-level bullying for the next 3 yea was a very difficult time. Catapulted me into weekly therapy, which helped, as I had no domestic or emotional support (still don't).
It was one of the best phone calls of my life to ring her to tell her I was going to a quite prestigious Chair. That department still misses me.
So doing HoD, plus pulling in a couple of research grants during my time as SL at this one place, got me a Chair at a bigger place, with HoD thrown in.
And they wanted me to "lead." Although I said in my interview I didn't lead in a macho invasive way: I prefer to lead by example, and to collaborate rather than come in and change everything - a model of leadership I see as damagingly masculine.
There's a lot of shit work you have to do as HoD, but if you can also have a small "management" team to help you, and a transparent way of working, it helps. I've always made workloads - teaching & admin - open and a matter of tabling & discussion in staff meetings. If there is grumbling, the data are all there - each person can see that if they feel overworked, others are doing pretty much the same.
Research: this is my haven. But I was lucky in that I have an ongoing research collaboration, through which - even in the Humanities (where I am) - we've landed a couple of large research grants. They got me my REF publications. And relief from endless mind-narrowing meetings about money & so on, into the light & air of ideas and knowledge & finding things out. Why I'm in the job in short.
But not everyone can do that, so if I were you I'd be negotiating either : normal leave before taking up the HoD post, or EXTRA leave after you've done your 3 years. One place I worked at paid me an HoD allowance, PLUS an extra term's sabbatical. The extra term sabbatical was worth more than the HoD allowance - that paid for a weekly cleaner so my one day off a week (Sunday) wasn't spent cleaning.
Salary: again, negotiate. You'll find it easier to get incremental accelerations, or if you're already a Professor, you'll be able to make your annual case for a pay rise easily. I've just done a year as HoD, and landed a nice pay rise which normally for professors you don't get unless you pull in a research grant.
Life/work balance. Ah well, I have none. I'm single & childless. Not a situation of my own choosing & it has been very very hard. No domestic or emotional support during difficult times at work. Paid-for therapy helped a wee bit even just as a sympathetic place to unload each week, and three years of that actually taught me a lot about how I work, intellectually & emotionally. But the job is designed for people who have a traditional wifey at home. Contrary to the prevailing view here, I'm afraid that life as a single barren woman is not as easy as people like to think.Alpjha women basically seem to repel nice men - at least that's been y experience. I've found ways to stop crying any time I think about my lack of a loving partnership, but it is tough. And the things I have filled my life with (like writing books and teaching) make it even more unlikely anyone will ever love me. I bear a sense of personal failure which tends to deepen any sense of professional failure (such as being bullied by a senior feminist). But this is a failure of which this society does not like to talk ...
Because I've done the job three times now, I'm pretty au fait with what needs to be done & what I can ignore. When you're new to the job, you think that budgets are important, but actually they are the least important. They're not going to sack you if you overspend. Indeed, it's good to overspend a bit, as it gives you ammunition to the centre to say you need more budget!
What really makes the job a pleasure (yes, even that!) is having a very supportive & trusting team - the best thing is that they understand it's a shit job, and you're doing everyone else a favour by taking it on.
And you can get things done, you can make good positive change.
In my most recent post, and continuing as I do now in another senior leadership role, I decided to be very "out" about being a feminist academic. And this has been a source of satisfaction to me - to have had an all female-leadership team, because we'd been successful in getting female colleagues promoted. As a professor & leader I can do this - although, as in many areas of work in this country , just by being a senior woman in the room is making change.
So, I hope this gives you some idea - in a very emotional, haphazard way - of some pros & cons. My main point would be: negotiate!