Your characters are amazing. Absolutely amazing. And they have only been getting better. I love the fuzzy ears that you have been doing, And also Rarities hair in your other deviation is ridiculous. It's been awesome watching you progress and improve.
Which is actually why I wanted to make this comment, your characters have really reached a point where they are unique and well defined, and you've always had a nack for dynamic poses, but I would really like to see you do a more traditional "study" on an area you could improve on.
I hope you don't mind me leaving a critique for your work, I'd just love to see you improve even more.
Your background looks like it was done real quickly, so all the focus was put in to the characters, but I would really like to see some background studies. Just quick things for learning, nothing overly done or finished. Like a value study. The main thing I notice in the background of this piece is there's nothing really implying depth, so at first glance the ground on the bottom looks like a floating island instead of the earth covered by clouds.
In your CMC boating piece it's the same issue, the water looks like one flat plain because there is no atmospheric perspective or value separating what is close from what is far.
I'd love to see you do a Value study, (And I don't mean that to be funny, lol) as in start with a 50% gray canvas and paint only using grey scale, and use the full range of black to white and see what you can create, and if you can culturally use atmospheric perspective and the separation of foreground and background.
For example: take a look at this piece in black and white: [link]
You see how the land at the bottom just floats, and there's nothing telling you that it's far away, and how all the clouds just sort of blend together? Right now you're separating these things with color, however color can only do so much, and to separate things from foreground background, far away and close, and show distance, is the use of contrast, either in color or value. Right now your colors are all very similar, with the exception of the land, but since the value is applying a reversed roll, we can't tell visually that the land is far, we have to guess, we aren't being told.
There are a few thing that you can take in to consideration to fix that. One: since the land is the background is very far away, atmosphere gets in the way, so it should be very light, and de-saturated, and you can even place a cloud or 2 in front of the mountains to give it that extra sense of depth. Two: the things that are in your foreground should be dark, think of when you place your hand in front of a bright light, how your hand gets really really dark and everything else is very bright, this is a common visual cue telling us that dark things are closer. So try darkening the clouds that are closer than the other ones and lighten the other clouds as they get farther away. This will greatly help with your sense of depth. If you take a look at the black and white pic everything is one big shade and there's no real difference when you take away the color. Your characters are slightly darker however, that's really good, you'll notice that it helps bring them forward. Bravo on that. I really like how you showed the light source behind them, it turned out really well.
I would have also liked to see where the light source is coming from more as well, a way you can try this without having to draw the sun is make the clouds on the right hand side brighter around the edges then the clouds on the left hand side. And to do that, you just have to darken the ones on the left. Remember that to often in art to make something seem brighter, you don't paint it brighter, you make everything else darker.
Other than that, that was what I'd really like to see you improve on. The more technical aspects of some of your background and core fundamentals. Your characters are beautiful, I have no critique for them. Just complement.
If you have any questions feel free to ask, I would love to help you out if you'd like the any help.
The thing with the mailbox broke me up. Maybe because I do exactly the same after posting a new work and I feel the same way seeing "oh, the deviantwatch message, oh well..." . (By the way, the scene broke my heart, it was so adorable!)
As for the work, I think it looks amazing! The angle, the dynamic of Twilight's wings and the choise for colours make this drawing special. Wow, those Twilight wings are just awesome! The shadows look very natural too. But what I love most in your works is that unique way they look. When some people prefer a "clean" colours, you apply some kind of a texture to your drawings and I tell you - that's a thing you should keep up doing!
On the other hand, you could work on the volume of their hair more. I think that Rainbow's mane is a bit flat, for example. I don't know if that was intended or not, that's just my reflection.
Almost forgot about the skies. You really chose the right colours for it. The clouds look very good. But a wild idea appeared! I just imagined this scene taking place above the water, where the island is surrounded by it and the right down part of the drawing would be water too! Oh my, those wild ideas I (only think I) can't even draw .
I love the angle you chose, and your use of perspective is nice too. What really stands out is how smooth the values are and how you lit your scene; you did a phenomenal job! I hope there's an episode or a few scenes with Rainbow Dash teaching Twilight how to fly. At least we know there's one scene like this in Season 4.