I use software like this on a daily basis, so here's my opinion:

Pros:

1. Nice that you can build interactions via the tool
2. Widely accepted by a large number of top brands
3. Well maintained with regular updates to the application
4. Prototyping functionality and can be tested natively to help you understand how your designs feel on mobile, tablet, etc.
5. Nice that it has a library of components which you can drag into your mocks, could be useful for a first iteration and rapid prototyping.
6. It has repeat grid functionality, although Adobe XD also supports this it's a tool which I regularly use and something I miss on Invision or Sketch.
7. They have support for both Mac & Windows.
8. They offer a free trial as well a free user package with a limited feature set.

Cons:

1. I may be biased here as I use other tools, but for the price past the free package, I believe there are more powerful and supported packages on the market.
2. Doesn't seem to offer a design spec functionality which you would see in another tooling, small but useful feature when working with development teams.
3. It might be there but couldn't find a well back community support behind this product. Sketch, Adobe XD, and Invision have a wide community support with constant UI Kits, tutorials, etc being created for it which helps with inspiration and quick prototyping.
4. I think the UI looks kind of dated when compared to some of the other design tools similar to this.