Hey Denis,
I just recently purchased GeeTasks so that I could access my google tasks offline (which is the reason I'm sure most people purchase your app). I've been liking it so far, but I have a few requests.
1. Tighter UI integration. I've read through the comments and I realize that this isn't necessarily your specialty but I just wanted to add my 2 bits about creating an aesthetically pleasing app. I would love the addition of some kind of "edit" button where I could rearrange, and delete tasks. I've created a mock-up since pictures are fun.
http://img100.imageshack.us/img100/4301/mockupg.jpg
I tried to use Apple UI elements to create a more integrated look. Now, I have absolutely no experience with this kind of thing (other than my ability to use photoshop) so I really can't say how feasible any of that is. But it doesn't hurt to dream.
2. Calendar view for choosing task due date. I was glad to see that you added the better date support at the top of the "date picker", but that could be improved or a calendar (similar to what the Google desktop version uses) would be super. It would help users to quickly add tasks, as the current method of guessing and checking which date next Wednesday (for example) is, takes just a few seconds longer.
3. Ability to tweak how date is shown. Right now it displays the date under the task in the form yy-mm-dd I would love the option for it to show "Wed - Nov 25" instead. I understand I can get something similar by choosing to display "Group: Date" but in that mode half of my screen real estate is taken up by those grey date bars, since I generally only have 1 or 2 things on my list per day. Just an option would be appreciated. (I also realize this is where notes are shown… but I never attach notes…)
4. Ability to view nested tasks in a sorting method other than "none". The second reason I purchased this app was so that I could sort my tasks by date, but this breaks the nested task functionality. This isn't a huge issue since I don't often use nested tasks but I would still appreciate it.
That's all I can think of after one day. I think the $2.99 I paid for this app is justified if you can continue to provide useful updates and are interested in creating a better experience for your users. iDevice users are becoming very greedy expecting great apps to be priced for less than a dollar, but I don't think that can really create a very sustainable environment for developers.
Looking forward to what you have to say,
Derek.