Really nice!! There's something I noticed about the scale of the plants. Somehow the flowers and the groundcover look a bit too large compared to the trees I'd say.
And regarding the lighting, (which I like very much, but maybe there's an even better setting?): if you use the RTP and play with the sun's heading and elevation, you'll maybe find a setting, where the lighting is still dramatic, but enlightens the scene a bit more. Just a thought...