My suggestions :
- during a time tracking session, force the screen to not switch off because of inactivity
- automatic dropbox backup
- automatic pauses every defined x minutes with an audible signal
- toodledo sync
- making suggestions right from the app
- being able to change fonts & colors
Making suggestions right from the app = just a link from a planmyday menu which opens a prefullfilled mail, ie subject already fullfilled, content mentionning the planmyday release.
For suggestion your ask, i would make it more appealing visually, when you see something pleasant for the eyes, you already hide part of what appeared as complex, people take care less and want to dive in beauty :). Look at Swipetimes Time Tracker for example, it's more complex than planmyday. Now look at the rating (good) and the comments (they are congratulations on the design, do you see people telling it's complex?).
I basically began to suggest font & colors changes made by the user but maybe you could take some inspiration for your slide left panel (today, finished, inactive) and task list :
For Left side panel, i would take example on 2DO app where the slide panel has good looking but also can stay on screen. This panel could list the toodledo folders.
For task list, i would take inspiration on Trello, each sliding column containing a task list related to a project (trello sync feature would drive people to your app by the way, especially the ones who don't want to pay a toodledo subscription).
So, on gui side, a trello like general layout and a 2DO GUI like task list inside this general layout. Their design is simple, smooth, clear and pleasant. We don't see these app as more simple than Planmyday but actually, they are more pleasant to see and use. This is appealing and i don't see people telling they are complex. Colors contrast help to organize zones and so help the mind to quickly identify what he is looking for and if it's pleasant along the path, i see it as a win.