The beams of light are very atmospheric but the screenshot suffers from the same problems as your previous ones - it looks far too pale and washed out. It needs more contrast in general, and it needs less pastel coloured textures and a shadow map with deeper, sharper shadows in particular.
I'd scatter some chunks of rubble around if I were you. Maybe add some stalactites and stalagmites. Regarding foliage, heed the advice that others have given you but remember that not many plants thrive in gloomy subterranean environments. Clusters of mushrooms and patches of glowing lichen might work well.
Remember: there's a difference between a location being conceptually dreary and aesthetically dreary. The former can (and in your case, should) be expressed in an aesthetically pleasing way, and this is what you need to work on improving. Pretty vague, I know, but I hope that you understand what I'm trying to tell you.
I'd scatter some chunks of rubble around if I were you. Maybe add some stalactites and stalagmites. Regarding foliage, heed the advice that others have given you but remember that not many plants thrive in gloomy subterranean environments. Clusters of mushrooms and patches of glowing lichen might work well.
Remember: there's a difference between a location being conceptually dreary and aesthetically dreary. The former can (and in your case, should) be expressed in an aesthetically pleasing way, and this is what you need to work on improving. Pretty vague, I know, but I hope that you understand what I'm trying to tell you.