The deep reds here can easily catch a person's eye when they're skimming through their list of deviations through their watch list. The blacks also make the reds a lot more intense, making this deviation even better at catching attention. In the middle of all of those warm colors, you then have a lot of cold colors (esp from Trixie) which demands plenty of attention. IMO, great for making people curious to take a look.
The shading on Twilight, Trixie and her clothes though, seem to suggest a very strong blue light behind Trixie in a setting that is completely red. Not sure if that was intended though, but I would imagine changing the background to better show a blue light would put a little less emphasis on the characters.
The blurry quality of the background also puts a lot of emphasis on the characters, which is a good thing as I like to think of backgrounds as just something to help set the context to tell a little story with just one picture. What's kind of curious is the lightly colored outlines on the leaves which doesn't seem to exactly match the blurry quality. (Never seen leaves look like that either)
I am also wondering how this piece would benefit if the characters were positioned to be 1/3rds of the canvas width from the right. I copied this pic into an image editor, cropped to exactly what I described, and found that the composition gave a much stronger feeling that they are moving forward. Putting them closer to the center like what was done here makes them feel as if they're idling more than moving around, arguing amongst each other. Not sure which is closer to your intentions, but that might be a useful thought.
You also forgot to draw in a tree on the top right corner.
Another thing I noticed was that the eyelashes seem a bit uncanny to me. A quick look at my own eyebrows in a mirror got me to see why. My top eyelashes are not only longer, but my top eye is angled in a way to partially cover my eye. My eyelashes on the bottom are shorter and are not angled to cover my eye. I believe this is the reason why manga/anime artists as well as show-style ponies seem to exaggerate the top eyelashes far more than the bottom eyelashes, because that's what people are used to seeing.
I am also not sure if you're using references or drawing from memory, but Twilight's face is bugging me a bit as the shading makes her nose appear very slanted on her face. Whenever I try using a reference then give form to a pony's face, I usually move the nostril away from the tip of the nose to try to create a form that makes more sense for a 3/4ths perspective. I usually find that my pony face would look a lot less slanted. I also remember pony (faux) anatomy to have a lot more cheek under their eyes, but I guess it can't hurt to put a transparent layer of a pony with the same head perspective to see what seems off so you can instantly see what you got right and what you got wrong.
All in all, you're definitely on to something, but I feel that better execution of pony head proportions might benefit quite a bit. You got the bodies and spike's proportions mostly spot on to me though.
Trix: Well, if Trixie isn't mistaken, it looks like Twilight is the cause of our predicament... Twi: I gave you the map, rememeber? You demanded responsibility on this trip! Spike: Hey guys, check me out! Trix: Trixie demands a Motel 6!! Spike: Guys! Twi: The least you can do is help me pitch the tent. Trix: What tent? Spike: This hat smells like jasmines. Twi: You didn't bring the TENT?? Trix: Trixie was already carrying the map... Twi: But, wha, but...? ARGH!!!