Tundra Hills provide 1 Production in addition to the 1 Food produced by basic Tundra tiles. Tundra Hills may be improved with Mines, which makes them significantly more productive than other Tundra tiles. All Hills have a +3 Combat Strength modifier, which can strengthen city defenses, as well as protect vulnerable units.
Similar to Tundra, the main problem with Tundra (Hills) is its lack of Food, which will hamper the growth of any settlement here. Unlike in Civilization V, you can never build Farms on Tundra, except when you play as Canada, so Housing is another issue for Tundra cities. The only two civilizations with abilities that make Tundra a little bit more bearable are Canada and Russia. Other than that, the only times you actually want to settle in the polar regions are when you try to secure a Strategic Resource, want to build the St. Basil's Cathedral or the late game Amundsen-Scott Research Station on one of the nearby Snow tiles.
Hills in tundra lands tend to be barren lumps, for the annual melt carries away the soil and seedlings. However, through history, most towns built in the tundra were put on hills ... which helped keep the wolves and bears out of the streets.