It's fine for features. The UI design reminds me of phone apps; you have to guess what the symbol means rather than using actual text, but for the most part it does it's job of facilitating office communications. Files are a bitch, but i don't have to use those in teams too often.
My hate stems from its godawful search, and the fact that it struggles to load goddamn text. I swear to god i can count the seconds for each scroll upwards and i hate it.