Looks like bad radiosity
which is actually good.
Seriously, big improvement
Maybe a bit more contrast would be good (less ambient light more sunlight). You don't need to stick with the numbers, it was rather a start point, but definitely we have some progress here. Glad I could help.
P.S. You might also try "sunset, sunrise color" switch ON in SunObject settings, sometimes it gives interesting results.
P.S.2 Remember about Brightness slider after rendering is done.
P.S.3 I couldn't help myself and mess with your rendering.