I love panels, honestly, I like them more than docks.
I would like to propose a couple of improvements if I may:
1) Pinning via mouse dragging; as far as I am aware it is not (currently) possible to pin apps by dragging them to the panel. I personally do not think it would take too much to include that feature in the future. Maybe an option to "lock" the panel would be useful to avoid pinning apps by mistake.
2) Preview; Ever happened that you find yourself jumping back and forth opened windows just to find it is not the right one? Including Windows preview by hovering the mouse over them could really come in handy. It is not a coincidence that many Desktop Environments have adopted this feature.
3) Status progress in the panel icons; ok this is me being picky! But improvement and progress is about the devil that hides in the detail! How about that nice GNOME feature that shows the progress at the side of an opened panel icon? (such as download or update progress) .
Please let me know what you think of this and I admit, they are minor improvements but that would add a lovely touch I guess!