To me, the worst thing InVision did was switching focus from developing the main tool to developing the Studio. Despite bugs and clunky flows of the main web interface, you can't deny that the original InVision was dead simple: I'm talking learning curve, ease of access, usage. All these things were the reason for such a huge adoption from the get-go and the reason for low churn in the beginning. Yes, original InVision is not sophisticated enough for advanced prototyping, but it is so simple that anyone can get started with it in under an hour. Had they built on this, as well as focused on integration with other tools, we might have seen a completely different story.