I've used it for auto generated diagrams of our code. Partly because it's what I know, partly because, surprisingly, there isn't anything free similar.
It's crashy for moderate sized graphs. And doesn't have quite enough layout and styling features. It's good enough but I'm on the lookout for something better.
Have you engaged the graphviz team? Maybe the don't have graphs of that size as part of their test suite, and if you could donate some samples, they would fix the "crashy" behaviour. No software should ever be "crashy" - it's buggy and bugs need to be corrected.
I've come across the same issues that others have reported. The answers have more or less been "contributions welcome". They have every right to say that!
It's crashy for moderate sized graphs. And doesn't have quite enough layout and styling features. It's good enough but I'm on the lookout for something better.