I'm impressed with this tool and this is my first ever review, but I think that some easily fixable or updatable issues will take it to the next level.
The reason I tried it out was the extended review from SaphireWolf. Agree about most points but having used it for a while I also wanted to share my experience.
I live in a country where all systems providing video calling are blocked and it's only by using our corporate network that this function works, but this is clearly indicated on their site.

Bugs quickly fixed
I raised an issue about sending videos and within a few days this was updated and resolved in a new version of the app, very impressive. I have just come across another issue but as you'll see it's a bit of an edge case: when using an ethernet adaptor on the smartphone the app considers there is no internet connection, hopefully this will also be fixed in the app.

UX/UI
I agree with a lot of comments on this point that the UI is simple but not really as clean and modern as some of its competitors. It is easily usable as is. I think that the UI could do with a complete revamp to help it compete. On the UX side of things there are some changes required, as explained above there are areas that are misleading or difficult to understand both at first and during daily use that need to be addressed.

The name is odd
One thing I really don't like about it, that often comes up for clients launching new products, is the name. I don't think it will appeal to quite a few people with such a name. It took a good review from a person I've come to trust for me to take the jump just because of this. Still I actually would not be prepared to use it with certain clients due to the name and would not recommend it due to the name. This is just my opinion but it has by definition a connection in peoples' minds to armed forces / infantry / war. It doesn't seem appropriate or even relevant. It is a pity as the solution really seems to be a solid one.

Default settings
You can define a PIN or fingerprint as a means to access the app on the smartphone.
I really like the fact that you can define the compression used on images shared, that is great.
There are some basic settings that are missing like being able to joing a call without video and being muted by default, the ability to define which microphone / video cam is used. Notifications don't show up with the app in the notifications area by default, not sure why but may be specific to me.

For me, it is a solid solution, it's a keeper, why I put 5 stars, fully stacked and I'm hoping the above issues can be resolved, for it to become a real challenger.