We use it internally at the company I work for. I wouldn't say it's a bad product, but I wouldn't say it's a good product either.
We've logged countless UX regression issues on their issue tracker and each one has taken 9 - 12 months to fix. Meanwhile, they keep churning out new features that we don't use.
I wish they'd just stop adding new features and spend 6 months fixing their UX and improving stability + performance.
> We've logged countless UX regression issues on their issue tracker and each one has taken 9 - 12 months to fix
Another data point: I've reported quite a number of issues, all of them have been triaged real quick, and many have been swiftly handled (the last couple were dealt with within a week). The longer ones are mainly larger scope (or depend on one thereof), or - wait for it - adding features.
> I wish they'd just stop adding new features
Every release brings a couple of features that we really enjoy having though, there's a balance to be had. BTW we're self-hosting and performance as well as reliability has been excellent. (disclaimer: happy EE customers).
I've been extending and updating the framework for a few years now. There's a tiny userbase but I like writing my games with it.