Playing around for 40 minutes with the text to speech converter:
Though it looks very promising simply playing around testing voices and pauses I couldn't get a good result.
Pauses between words and sentences can be set but the converter doesn't react when changing pause length. Changing voices created different outcome but I was not able to understand why and what caused these different outcomes. Felt like I had zero control over the voice settings. With some voices, the highlight spelling option didn't work. Changing the speed once created a loud click in the audio file.

Help center:
In the help center I couldn't find any brief description on how to work with the pauses or converter settings. A simple search for 'pause' didn't give me any useful results. Even the helpdesk article 'How to create a voice over using Listnr' doesn't explain how to use all converter settings... That hurts.

Taco's:
Would be 4 taco's if all converter settings work as expected and even 5 taco's if they added simple and short video tutorials, showing all the how to's and proof it works. I believe any app should have tutorial videos nowadays.
Looking forward to explainer videos and the converter settings being fully operationable.

Roadmap:
Personally I would focus on improving the converter first and than anything else. The whole idea about text to speech converters is that they sound awesome and make it easy to achieve the wished for result, saving credits by not having to test over and over again...

If these things are fixed I will keep the app.