"Add-ons are available! Select this banner to purchase them now!"
Doesn't sound too free. Some things are free (skins you can unlock) but it looks like the new courses are paid.
EDIT: Courses:
Mountain
Big Eater
Championship III and Highway II bundle
$2 each.
Skins:
Dug Dug
Rally-X
Pac is Back
$2 each.
BGM:
Pac-Steps
Reentrance
$1 each.
It looks like there's supposed to be a bundle of everything but it's not on the store. (Maybe the store hasn't finished updating.) It doesn't say how much that's supposed to cost.
You unlock a skin for getting all the trophies and earning all the new medals (like trophies but don't get added to your trophy list) but I don't know if it's one of the paid skins or a different skin.
New interface is awful.
Cluttered and ugly with tiny, tiny text. The medal descriptions are tiny green text on green backgrounds that only appear when you press X and then disappear after a second before you can finish reading.