I know this is a prototype tool and I do not like to criticize, all I'll do with this review is to make the tool better. And that's my only intention.
The first thing that bothered me is a black&white technique, just do not tell me how the prototype tool must be black&white because that is not true. The second thing is that there are no tutorials like how to use it with your domain or any other tutorials. Everything that is bought today and is related to web design must have tutorials.
Another thing that should be is that you can use as a team, at least 2 team users. It says this is a tool for agencies and only one user can log in so it does not make sense.
I decided to give a chance and try everything I can with Draftium but for now I'm not sure if I will leave or not.
Once again this is not a criticism, I have no need to criticize this is just a suggestion that will prevail for me on the end, to use it or not.