The first thought about this movie is "Not another movie about coal miners, strikes and the impoverished mining areas of the UK". However we all loved Billy Elliot, Brassed Off and the Full Monty, so there is no reason why we wouldn't want to see another great movie from that era.
Also the mining communities stand in for us and our resistance to change without actually being us. In this case, they can both be uncomfortable with the Gay and Lesbian community while also being sympathetic characters because in the end they embrace the change.
While based on a true story is usually movie slang for completely made up and nothing to do with the truth, this movie is based on the work of the groups that would become Lesbians and Gays Support the Miners alliance. In the 1980s Margaret Thatcher was taking on the unions and most prominently closing the mines. To break the strike action union funds had been frozen which meant that many towns throughout the UK were without jobs or any income support, so various groups were encouraged to provide support directly to affected communities rather through the union.
Pride obviously simplifies the story somewhat, as it also simplifies the characters. The Welsh miners are all simple innocent people and the gay and lesbians more or less deal with the same problem of being nice people who happen to be completely gay.
This is the appeal of the movie. It is not an in depth analysis of issues surrounding, unionism in the UK, Thatcher era politics, police brutality, the broad rainbow of human sexuality and Gay and Lesbian issues in the 1980s. But why not, there is no reason why we can't enjoy some fun light entertainment where half the characters happen to be gay and the other half from a Welsh mining community.
In the end we have a funny, well-acted movie with an eclectic cast telling a positive story with great heart At the same time it doesn't moralise or preach while still touching on some deeper issues.