I've used it a little bit for a Google App Engine app.
The built-in debugger is very impressive, you can print variables in production code without slowing down (at least on Google App Engine). The exception tracking view is nice although not as detailed as Sentry. That's about it for the good.
The bad:
The web UI regarding logging is absolutely awful. It's quite slow, the query language is IMO not very intuitive, but worst of all, linking to a particular log entry is horrible, and the current view isn't persisted in the URL so you quickly become scared of anything that would reload the page as you'd never find where you were before. I have never dreaded looking at logs as much before. Usually it would be the logs themselves that scare me, but in this case it's the tool for viewing the logs.
It's also Google, so there's some creepy telemetry to stalk your console behaviour. I couldn't believe it when I first saw a toggle for that somewhere deep in the user settings but looking back at it I should've expected it coming from such a company.
