Why are people against the Obamas public health care plan?

As someone who's had cancer twice right after college, and couldn't get any insurance to cover me - including the insurance that I had previously under my parents, I like that there's a health plan for people like me when you can't afford high priced insurance or when they reject your claim. Like my parents insurance rejected me after I got hit with cancer the first time & left me in the lurch. :( But I want to know why others are against it because obviously my history makes me biased.