Very nice! I love the style! And uh.. since you wanted a critique:
The good:
-I think you nailed the rain effect you wanted.
-I love the highlights you added on his chest. It makes it seem like he's gazing at the moon.
-I love how lit up his eyes are, it really brings the focal point to his eyes since they stand out so much.
The bad:
-You should fix how the hand holding the rose is drawn. It kind of seems like the rose could easily fall out of his hand because he's not gripping it hard enough.
-I don't really know much about roses, but maybe you should have the leaves droop (especially the one that's pointing up) since it's raining and the water would make it sag/heavy. And maybe his thumb needs to be adjusted too. (Just try holding something, like a pencil and see how the thumb is positioned)
-It could be my personal preference, but the highlights of his hair (specifically this bangs and the top of his head) are too bright.
If you still want to work on the tree, why not blend it more? And instead of making it look "blocky", use long vertical streaks.