Craft, from the company of the same name in Tel Aviv, is presented by the vendor as a better way for Product Managers to manage and plan their products in agile environment.
Craft.io is well suited for medium to large digital product teams that have some experience with the tools and features of the agile and lean models. Users that are new to those methodologies can have some difficulties understanding the platform. It is less appropriate for small projects too. It's a great tool but I think you can shape a project management tool to your needs in theses cases and it will work better.
'Sync' usually works flawlessly in syncing my artboards to Invision. Once you set up the plugin, I can easily forget about tinkering with any of the settings - it just 'works'.
'Library' is pretty great for generating a style guide from my design doc. Clicking one button makes magic happen, and creates a super succinct document for me to share between teammates and other teams.
'Data' also works wonders when trying to approximate 'real' data into a static design. It turns the painful job of having to fill in designs with 'real-world' data a piece of cake. It helps me validate rough designs using an actual approximation of real content.
Craft has a completely unique tool set that has functionality that really is not duplicated any where else in the industry. It cannot really be compared to any other tool I have had experience with, especially with the larger cloud infrastructure that Invision has built around their plugin and their platform.