I don't know why I waited so long to read Janet Kagan's Hellspark, given that her Uhura's Song has been my favorite Star Trek novel (and one of my favorite books in general) for over twenty years, but I've read it now, and it is just delightful. If you like culture stories, first contact, interpersonal dynamics, lots of weird SF-nal invention, and fun play with language, you'll love this book. Shades of Suzette Haden Elgin's Native Tongue.
My only caveat is that the first chapter or two is a little heavy on the invented / capitalized words for my taste -- it goes beyond enjoyable / interesting to annoying and a barrier. A common issue in SF/F, I'm afraid. But once you're past that, you're good. Really good.