Well, the stones look a bit awkward and leaning too much, but the grass and river and far behind mountains are very good, with a bit too much gloss on the pony and her face needs more work. Other than that it is a very nice piece of artwork! Sorry...
I was actually stupid enough to replicated how the scene looks in the episode itself, where the mountains are rounded. Which is a problem as such formations don't exist in real life. Thank you for pointing that out! And have you seen the revised version?
Wow! I can understand why you'd revise this to look like the other version but I prefer the vivid colors in this one, personally. This is gorgeous! I hope I can produce stuff that looks as great as this someday!
I'm not getting the feeling of scale though... I see her at the ledge look out over the mountains... but I don't feel it. To add "feeling", you need to address the light. Light is what composes a scene.
Right now with the levels of contrast and saturation of the hues, the scene looks very disjointed and disconnected. You need to unify the light within the environment.
I hope you don't mind, but it's easier to just show you: [link]
Also, you painted this lovely scene with fantastic characteristic brushstrokes that give everything a nice texture... but Rarity is very smooth... The difference in rendering technique between Rarity and her surroundings makes her look out-of-place; and not, "royal unicorn trekking across the equestrian frontier" out-of-place. So you either have to render Rarity as roughly as the environment... or you have to render the environment to the same level as Rarity. Personally, I think you should avoid the over-rendered smooth look (for now)... because you'll learn more by keeping it loose/rough.