I lost at least 20% of my working hours trying to get the project to work again or waiting for it to sync to asset server and would always be half hopeful and half terrified at the time of any updates to Unity. "Did they fix the unresponsive 'cancel' button on the assert server update action?", "Did they make it more stable?", "OMG! Another update! Will my entire project re-import again?" were the kind of things that used to run in my mind.

I'd have to hear strong positive reviews from those I trust to even try Unity again (assuming they back them with good reasons).

Unity is really nice, and if you plan for it, can scale pretty well. It's much more flexible, so it's easier to shoot yourself in the foot, while other engines are less flexible, which can be advantageous at time. Additionally, it's difficult to get it to shine at the higher end in the ways that other engines do. IMO, I think this is more of a problem of bad defaults than any significant lack of features. But the top tier games released by most of the other engine developers have really forced them to tweak the engine in ways that Unity has not.