I used to work in HR. I had to think twice about posting, but then thought you asked for opinions, so here goes.....
I mistakenly wanted to work in HR as I thought that it would be a great place to help people get the most out of their jobs. I really enjoyed finding good people for tough jobs (it was for a start up organisation), but hated the rest of it. This was for several reasons:
I'm actually more suited to creative project management jobs (eg marketing, which I do now), and I found HR was more of a scientific job, with lots of repetitive elements and lots and lots of record keeping.
Rather than helping people, the job I did was much more about protecting the company, and I felt we screwed a few people and exploited some others (I was v v uncomfortable with this!). (Sorry, not sure if allowed to use 'screwed' in this context!)
I felt a bit out on a limb - HR people have access to personal records, details on disciplinary hearings, etc, etc, and were, in my experience, viewed like the police of the organisation, so held at arms length by peers in other departments.
Apart from appointing people, the only other time we interacted with employees was if there was a problem - disciplinary, pay issue, bullying, etc. Giving bad news (redundancy, for eg) or having to confront a difficult situation (drunk at work, for eg) is, at best, character building, and at worst, a total nightmare.
I was also shocked to find out how much people try to play the system and get away with things that are totally not acceptable. It opened my eyes, and made me realise that I wasn't tough enough for that area of business. It's really hard to have to negotiate with/confront someone who is significantly more senior than you.
So, as you can see, I didn't have the best time. However, I'm sure that there must be someone out there who enjoys it and works for a company that was slightly more ethical than the one I worked for so I hope you get the other side of the story! Bottom line was that it didn't suit my character and personality, so my advice would be to think carefully about whether it will suit you!