Great, as usual. But don't you think it is... empty? Rarity is already white... with the white background... And actually, I wonder, is she laying on the ground? (more likely to since that's what the title is all about) but the pose don't seems very confortable. And she's layed in a weird way... like if she was floating.
Magic, my friend. Magic!
Maybe she's a little too slim on this pict? She would need more mass in her front hooves?
Anyway, there's something wrong with the pict... I wouldn't be writing all this if it would not be the case............. OK! It might just be me being not an expert in drawings, it MIGHT be the case. But I still think, as a Young, French, Canadian, Gamer, Brony, writer, that this Rarity looks weird and the pose might be revisited...
I hope this critique help you being more awesome.
Oh, and also, All the rest looks great. Keep up. Maybe once, when I have a PayPal account on, I will ask you to make my OC... I just hope you won't be flooded with commissions 'till then...
If it's the case, we'll just go back in time and ask for the commission earlier.