Based on almost a month of Sencha usage, I came up with the following suggestions

1. Adding a keyframe to existent animation

Now when you want to add a keyframe between two keyframes by double-clicking the timeline it just moves the previous one to the point you clicked.
So the top point is - I'd like to add any amount of keyframes between any two keyframes and manipulate them the way I want.

2. Animating multiple properties on a timeline
An object should have a separate timeline for each of properties animated, nesting is ridiculuos

3. Moving keyframes on a timeline
I'd like to see a feature of moveing any amount of keyframes of any amount of properties over timeline. It's good when you have to change overall timing of animations.

4. Motion and speed graphs
Custom easing graphs is good but what is really necessary is motion graphs for better, smoother animation

5. Graphical editing of motion path
The best example is Adobe After Effects or Flash where you can define a custom path of any complexity for an object.

Hope at least some part of this will be included in future releases.