It depends on what you want, maybe they help you in some cases because it costs nothing, or doing so does not touch a "live wire" of corporate policy or government regulation.
But for other matters, HR does pursue their own agenda, not yours. It's important to remember.
When I worked in retail my name and zip code was incorrect in the company records. When I asked who I should contact to fix this, my store manager told me I'd need to contact HR but to never ever do that. I'll always wonder what would've happened if I had contacted them.
Then to be perfectly honest they are bad at their jobs. The purpose of HR is to protect a company (which in practice means, its senior managers) from the employees.
No, the purpose of HR is to manage one of the company's most valuable assets. Acting adversarially is a great way of driving away the most valuable assets.
