Issues Screenshot
In a sense, no it won't pickup your forum's theme as well as before. It's a slightly different style simply because of how much stuff is in it - using MyBB's trows and tcats would have made it far too bulky and disorganised, but I think I've made it as clean and as simply as possible!
Of course, you're free and able to edit the templates through the MyNetwork system and stylesheets to match your theme. There's nothing stopping you creating your own custom theme that does follow your forum too, and it wouldn't be too hard to do.
This time round, it closely follows Redmine. Essentially, it's the most powerful bug tracking software available for any forum system.