This is great work on the whole, the way you've done the light and shadow is great, (especially with the creases in the shirt), the mood and subject is really nice, and both characters have been rendered in a very natural and non-explicit way.
The only real criticism I have is the way Summer's mouth is drawn. I know that drawing a character's mouth on the side of the face like this is a very common style in anime/manga, and I normally wouldn't even point it out, but the fact that Taiyang is kissing her in this picture makes it look a little weird.
The rest of her face/head looks like she's facing towards him, like she's kissing him back, and it even looks like there's the outline of their lips touching, but the way her mouth is drawn makes it look like he's kissing the side of her cheek, even though that's where her nose is.
It's a GREAT picture, but just that one tiny detail looks weird.