I've worked in HR for a FTSE100 business for 8 years, starting in recruitment but have recently been doing a more business partnering role. On the whole, I enjoy it.
There's so many elements to HR, it really depends whether you want to specialise or be more of a generalist. Personally I prefer my business partnering role as its so varied, sometimes this makes everything feel a bit overwhelming but I found in recruitment, once I'd done it for a year or so, it got quite repetitive.
You do have to get used to being seen as the bad guy, my company give HR quite a lot of grief about being slow and inefficient whereas I find (having worked in both central HR and the business) we are actually more enlightened and progressive than the business.
Being involved in tribunals and grievances can be quite difficult, you have to develop a thick skin and try not to get too emotionally invested.
Get used to telling people no quite a lot. But that's balanced by helping find solutions to their people problems.
If you're serious about a career in HR, you really need to get your CIPD qualification. I'm doing my Level 7 currently (only done 1 module) and so far it's a bit woolly and hippy for me but it's essential to climb the career ladder.
Hope that helps!