Maybe remove the main cloud and add other clouds far away in the background.
@Theoden. I maybe wrong here, but I believe that the rain drops are coming from that cloud only, so there would be no need to have rain drops over the cloud. Also the size of the rain drops, if adscomics makes them look any smaller then they may end up looking like dust. I think the issue here is just merely lessening how much drops there are on screen. It doesn't need to be over complicated.
Looks nice but the clouds should be as dark as the other scene elements when there is no lightning.
And rain drops should cover the clouds too. It looks like it is only raining under the clouds and not in the vicinity of the camera. And if it only rains under the clouds then the rain drops look as if they are huge if you think about the size of the castle. Render different sizes of rain drops at different speeds on the "entire screen" and it will feel more realistic. Smaller (further) rain drops should fall slower relative to the bigger (closer) rain drops to simulate their distances.
Sorry 'bout that. Apparantly when I looked at this post, I was a bit grumpy.
The rain is a bit to much, less raindrops could be better
Also the clouds could cut off at the top so that you can't the the black skye over them.
The idea and the first look is graet i think :)
This looks much better with the lights and the rain adds a much more spooky feel.
One nit pick - with the rain, I would make it look a little less dense as there is a bit too much of it at the moment.
@BathMaster. " you don't really know what you're looking at until the lightning strikes." I think that is what's supposed to be happening. adscomic has executed that part well.
Make the silhouette of the castle and the mountains stick out more from the sky, you don't really know what you're looking at until the lightning strikes. You should move this project over to the forum thread, you'll get a lot more feedback there, and you won't have to repost the thing here every two seconds.
I don't like the rain much, it looks like you rushed it... 
Better with the lights like this though. The clouds are stickout out too much compared too the rest I think (too saturated).
Any ideas? I did just add some rain, I'm open for anything else though
Pretty good, if not just a tiny bit too basic... you can easily put more work into this to make it look awesome.
I was thinking about the lights, but I feel that it'd look weird over the blackness. I'll look at it again though
I agree with Aerofyn/Zizka.
I would also add some rain to complete the spookiness.
But still, in pitch darkness, you would see the light from the windows I think, regardless if there was a lightning bolt or not.
Because they're reflecting the colour of the lightning? :)
I really like this! However, there is a problem. When the lightning flashes, the build is revealed, and it appears the lights are on. If they are, why can we see them when the lightning is not flashing? Other than that, it seems perfect.
That sounds like a good idea actually, I might do something like that