What do you like best?
I'm using *several* forked versions of Hubot for a variety of teams. One for our company's internal Slack server, and two more for small online communities I manage. The number of community-developed (and tested) integration points for Hubot, and the ease of writing customized plugins, makes it an invaluable team automation tool.
What do you dislike?
Connecting Hubot to multiple "adapters" — services like Slack, IRC, and so on — is pretty much impossible. Choose the realtime service your team will use for communication, and connect Hubot to it. If you really have to bridge multiple realtime communication services, Hubot's just not up to it.
What business problems are you solving with the product? What benefits have you realized?
We've wired out bot up for everything from realtime PTO/OOO tracking to project update notifications. Hubot isn't about a single killer feature — it's a tool for quickly smoothing out the rough edges of a team's communication. For distributed teams, it's especially useful.