A friend is being published there. The first novel in a three book deal is now highlighted on their website--Arizona War.
She's enjoyed working with La Frontera, and I believe her novels will also be available through UNM Press. I don't know details beyond that, but I'd say they're completely legit.
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edited to add: This has nothing to do with working with this publisher, but I have a copy of Arizona War. It's got a great cover, and the pages are easy (and fun) to read. And to toot my own horn, the author thanked me on the acknowledgement page. I did some editing work on an early draft.