I feel the author of this ToDo List really knows what simplicity is and its strength. I have never used any ToDo List that is easier to use than this one.
One thing I noticed is that it does not even have a time frame/progress indicator for each ToDo List item, but for most personal uses, that's often not a problem.
There are only two files included in this app as of (one of which is the flatfile database), which makes (un)installation so easy and quick and clean (very, very important, IMO).
If you want a ToDo List, I mean, nothing but a ToDo List, go for this one.