FWIW I think you should keep the functionality as near to Google Tasks as possible!

1. Create/drop/rename a list. For many people the thought of it not being there simply never occurs before purchase so they get really upset when they don't find it and feel cheated. I don't want anybody to feel cheated and it seems no amount of documentation will help me because the expectation is very deeply rooted.
2. Consolidated view. There is a lot of demand for cross-list view of tasks in the Google Tasks support group because Google does not support it currently and people with many task list feel essentially blind and unable to know what's to be done in a given day. The Google's design was to have one task list for each context (e.g. phone calls, work, shopping) so that you switch to a task list for the right context and do only those tasks. However many people don't use it that way. If I implement this I may sway some of the people who previously didn't consider iPhone app at all. :-)
3. Font size. Lots of people want to see more of their tasks on one screen, but different people mean different things by that - some want to have more letters per task (smaller font, multiple lines) some want more tasks per screen (single line, smaller font).

So on the bright side, your request is in the top three. On the other hand, I think it will be the last of the three to be done. I'd give it 4-6 weeks to get the beta build out.

I'm staging the release so that if something goes wrong fewer people are affected.