The main rub is:
Employers have incentive to turn full time employees into part time workers and to hire more part time workers so that they escape having to buy medical insurance for their employees.
Employers have incentive to offer "minimum essential coverage" to their employees if they don't provide coverage to all their full time employees. This is because of the strong and weak penalty provisions of the law. Full time employees who have good insurance are likely to have it replaced with "minimum essential coverage".
If you like your coverage, you can keep it.
In response, President Obama has said he will delay these requirements for 1 year?
Walmart has already responded by reducing their full time work force.