What do you like best?
You don't need to worry about reporting rates etc, Raygun will just accept everything your system can throw at it. The interface is very good, and useful for tracking down the exact piece of problematic code. We've got everything linked up with Github, Trello and Slack too which means we can create PRs to solve bugs, or Trello cards to track more detailed resolutions and we get notified immediately when something happens in Slack.
We have user tracking enabled too which means we can often reach out to a customer and tell them we've fixed an issue before they've even had a chance to email us! Hooks in quite easily with our custom app which is nice - we can report both the user specific information and their account information.
What do you dislike?
It's relatively expensive, but you definitely get what you pay for.
Recommendations to others considering the product:
Give it a go, make sure you do the full integration and try everything out rather than just the error tracking piece.
What problems are you solving with the product? What benefits have you realized?
Error tracking and Application Performance Monitoring for two startups. We've seen faster time to diagnose errors or performance problems, and much more confidence deploying new code. You get line-by-line traces so you can look through and figure out exactly which line in your code is causing the problem. Super nice!