Many times I find it difficult to select a subview under another subview. Or, when adding a subview, it is too eager to be the subview of a subview. Those are the tip of my list of grievances.

I use it! Sometimes it's simpler and faster to go with IB instead of code, and you are definitely right about maintainability. But I sure wish there was something as convenient that wasn't awful to use. That's actually how I feel about all of Xcode. (Yes, I've tried AppCode, I liked it even less.)

And of course, this tool isn't just for UI tweaking. It's for any kind of messages you might want to send to objects. It's an object spelunker.