ELI5: America's health care reform

What about our old health care system are they reforming? What are the pros and cons for users/patients? What are the pros and cons for doctors?

I feel like this is a huge issue that I need to know more about, but whenever I try to read up on it, I get so overwhelmed! Can somebody explain it like I'm five?

Edit: Great answers you guys, thanks so much! Also, how will this affect physicians and their salaries? Who is making/losing money from this reform?