This makes sense.

1. Talent: As others say, an all star team. I've interacted with some of them as a vendor (Quip is our customer) and know a couple of them as friends of friends, and they have a rockstar team.

2. Integration: This is going to add collaborative document sharing to Salesforce's product line. Much like the Chatter acquisition to beef up their "collaborative, connected customers" story.

3. DATA: Essentially, Quip's metadata is the intra-organization graph of who collaborates with who. While Salesforce needs to be careful how they are going to use it (and definitely need to create the technical infrastructure to take advantage of this data), this is a deep well of customer knowledge that they can parlay into selling other Salesforce products.