The tree shadow is way too sharp and the image has gotten a bit dark. The farther away an object is the softer it's shadow is going to be. The plaster still needs a lot of work, it's the largest part of your image. No matter how hard you try, a flat color with a even texture is not going to look real. I did a render that's a lot like what you are working on. It's not as far as I would take it but it gets the point across. Here's some notes about the render, not much new from the other posts
The model is rounded and slightly irregular.
The wall has a photographic color map (below) and photographic bump map (same as the compass above). In this case they are different textures, a plaster/stucco is a painted rough surface, the color often has little relationship to the texture making 2 different maps work just fine. The textures were projected (Tri-Planar) instead of UV mapping.
It's shot off angle.
It is lit with a shadow casting spot light. A slight noise was used in the lights color to break it up.
A grey scale HDRI was used to add environmental light to the image. I use grey scale HDRIs to keep out extra color casts.
Final Gather was used to add Occlusion to the render (Radiosity in your terms).
I added the palm trees image (above) in Photoshop as an Overlay.
That's it, I'm at loss to tell you anything above and beyond that.