I have plenty of horror stories from the pre-ACA era.
Also, I've been on record from the beginning that I don't like Obamacare...mostly b/c I despise the health insurance industry as a whole.
That said there are obvious things that can be done to fix the current problem. I think 2 items alone would fix most problems, 1) remove the mandate; 2) add a low-cost (bare bones plan) public option. With the low cost public option, the subsidies would go straight to the people that need them, and not through the for-profit insurance bureaucracy. The for-profit insurers then also don't have to take on as many high-risk individuals as they will be on the public plan.