How does ObamaCare affect Medicare?

Very little. There are some minor funding changes and small changes to the reimbursement schedules, but, as a whole, the normal senior citizen will see very little different. The sole obvious change will be the eventual elimination of the Part D "donut hole" covereage gap.

Otherwise, nothing has changed in how the plan operates, who is eligible, etc.

Now, the Medicaid program (assistance to the poor) has undergone significant changes, so please look elsewhere for that answer.