I've been using Butter for many months now, and their team has done an amazing job taking feedback and integrating it into the product. It's great to have a centralized way to find all my files across all my (many) services!
More connectors and more data to learn from will make it better over time.
Several times a day I have these brain fart moments where I'm looking for some work document and need to grope around my Google Drive(s!), Evernote, and Dropbox to find it. Now, I just ping Butter on Slack and it does that for me, without the blind mindless searching from one service to another. It's great.