Those commercials are annoying and borderline dishonest. They give you the impression the Federal Govt. is holding out on you, not telling you all that's available.
My wife and I are on an advantage plan. We're quite comfortable with restrictions on choosing a primary care doctor and staying in network. We're in a small town so it doesn't make much difference. We did discover it was better for us to sign up with a locally based insurance company. I suspect the plans are most appealing to people who don't have a lot of serious health problems. Our prescription coverage is better than we had through our employer's health plan. The advantage plans make more money when you stay healthy, so they have gym memberships and other incentives included. A membership to our local YMCA is a nice perk.
If you're interested, the best place to start is the Medicare website itself to get an idea of regular Medicare, supplemental insurance and advantage plans. It seemed overwhelming at first, but it really wasn't difficult.