+1 for having the willingness to roll back to a previous version if that's what people wanted! I know too many people who would have said "This is the new version; deal with it." Refreshing to see you listen to your customers so well.
Having said that...
I liked the new design on iPad; it somehow managed to fit more into a display at once, and I also liked how much faster I could navigate between folders. One thing bugged me, though - if I was looking at 'Today', and then came back the next day, it would still show that day's tasks, without refreshing the screen. I had to go look at tomorrow, then back to today, to make it refresh "today". I like how the old version refreshed the current folder on opening the app.
While the new design was good on iPad, I find it hard to use on iPhone. I still see more at once, which I like (such as the small-font folders, repeat status, date under the title - great addition, btw). I suppose the biggest thing that feels awkward is how badly it cuts off button titles - especially if using a non-English interface. The button for Add Task for example doesn't grow, and you see "Aggiung...tivita".
Whichever version you decide to stick with I'll still be a happy user. This is easily the best (read: only) todo manager for my way of thinking.