Guys, I’m not sure its useful to keep comparing UE4 to anything else. The fact is, we should expect perfect stability and usability as the target no matter what it is we’re using. Of course that can never be achieved, but the question is how do you move towards that goal.
The issue right now, is that there are still plenty of crash/breaking bugs. Once my schedule is a bit less frenzied (end of term) I’ll do a quick test and see how long it takes me to crash the engine or find a feature that causes what would be a game breaking bug. We used to do this kind of thing on the games we were making for consoles. If you could make it beyond a specific time (think it was 24 hours, but can’t remember exactly) you were OK to ship.
I highly doubt you could get UE4 past an hour. Which I don’t think is what you’d say was acceptable for mainstream software. Of course we all learn where the majority of mines are in the minefield and learn to avoid them, but I think if there’s going to be real progress you have to start thinking about tools for mine detection for instance 
It’d be really nice if things could get less about specific feature sets and more about how to engineer a better process for this particular aspect of stability and usability. How does the engine team plan on improving their process etc.
Honestly, I’ve been out of mainstream game dev for a while, but I remember that with the best will in the world, game code was never really engineered for long term stability. But I think the circumstances of the new engine model should maybe give pause for thought on the development process. I appreciate that Epic have gone to this preview build model, but to me that is like trying to fix the door after the horse has bolted. Sure we can help test, but testing isn’t really the issue, the issue is code quality in the first place. Fixes earlier in the pipeline usually give far more benefits. So things like better code review, more discussion of public API designs, actually trying to think long term how to improve development process etc.