Every job has their negatives and positives - you need to sort out if the negatives are something you can deal with. I think you need to sort out what area of Human Resources you are interested in too - is it Compensation and Benefits, Recruiting or a HR Manager or Generalist for the employees in a company.
The negatives I found working as an HR Generalist is that it can be stressful making decisions affecting peoples lives -terminating someones employment, laying someone off or deciding if they are getting a promotion or not - all of these decisions affect someones life so you need to be comfortable making these types of decisions. If you are working directly with employees as their HR person you are the person that has to deal with a troublesome employees safely.
There are a lot of benefits with working with people too - just as you get the bad you get the good - it is very rewarding to see your people grow, be successful and to celebrate accomplishments with them.