I’ve been using the previous version for a while now and it’s an amazing app, and wouldn’t have had any problems to pay a small amount for an upgrade. Sadly the current app does offer new features, which look promising, but as it is locked behind a subscription model, I will look for a substitute.
The app itself is very intuitive to work with and offers a load of options. I generally use it to summarize books or create a mindmap to visualize the skeleton of a paper. A handy feature is the export functionality, which I used a lot. If you are still able to get your hands on the previous version, I’d recommend getting that one. I am not sure whether the monthly/yearly fee is worth the upgrade.
Crazy thing is that I read in a previous review that I am using a very old version (4). Which might say something about the app or me or their way of communicating over upgrades. :)
What I do respect is that the developer seems to respond to reviews. Which is great!