Repeating task interface as good as google calendar.
Repeating tasks are really great, but todoist doesn't go that far with them. For example, it is missing the ability to set a stop date, move tasks around just for one repetition without altering everything else etc. . I urge you to look at google calendar here, gcal does this quite well.
I am dropping my premium subscription at end of the trial because it didn't provide any value to me. Functionality like this would easily make me stay subscribed.
I have actually moved in the other direction. I am now experimenting with Todoist as my personal calendar in preference to Google calendar, and so far I think the switch has been worthwhile. The combination of tasks and diary events is handled much better in Todoist, where both can be integrated into a single view. However, the provision of better repeating task functionality would be a very welcome improvement. In particular, the ability to handle exceptions to the repeating pattern, and the ability to describe the repeating frequency in many more ways. I think the latter is the subject of a separate suggestion.