It looks great! All the water that is on the rocks is that splashing from the fountain? If it is, you may want to dial it down a tad as you'll lose water on a regular basis and have to continue to fill it. You can add a little osmocote to the kitty litter as fertilizer for the potted plants.
I have tried a bunch of plants in the pond, if they start to look sickly, I pull them out, plant them in the ground, and try something else.
And I didn't see, but did someone tell you to make sure it is plain unscented kitty litter? The cheap stuff.