I have to say that in all honesty this is a hit-and-miss kind of thing. Let me explain constructively why this comes off as a 'meh' for me and what I personally feel the author could do to improve.
-Tittangas (Wow those melons)
-Familiar characters (Riding on the popularity)
-TITTANGAS (Cannot overstate the importance of this, as it is the main pro)
-I'm really digging the previews of Rarity and Fluttershy, although I couldn't honestly state a review of the full image for a reason I will explain in the 'Cons' part of this critique.
-Your use of color is amazing.
-The eyes, especially the colored portion, are perfect.
-The face shape doesn't look too refined. Rainbow Dash probably being the biggest example. Her face is, not to be rude, not of the highest quality. And Twilight's jaw is literally a triangle. On the flipside, I really like how Rarity looks as that face shape fits her, but it can't just be a go-to thing for all of their faces as it is a technique for drawing that is generally abandoned once your art isn't amateur, and certainly abandoned when you're asking money for it.
-Let's all be honest here, in this day and age, there is literally tens of thousands of pictures just like these of an equal or higher quality and not a single one asks for payment. In my honest opinion, a better way to go is to ask for donations, because if you're going to make people pay money for something they can easily get for free elsewhere, you aren't going to stand a chance against any of the more renowned artists out there. Besides, I'm sure you'd make more profit off of lump-sum donations than a forced fee to view the art in the first place.
For example, if somebody donated $20 to you outright, that would be the equivalent of selling ten copies of this. If you made your art special and refined your technique I'm sure there would be plenty of people, myself included, who would make such lump-sum donations, but as it stands now I am sure I speak for many when I say that asking people to pay to view your art is kind of ridiculous, especially when it has some questionable quality standards.
-I must again emphasize that the fact you ask a price for the ability to view your art will majorly damage your ability to reach a target audience, I'd like to tell you the fact that you're likely going to drive off many people who would otherwise be fans of your work. If you insist on keeping this pay-for-artwork method of distribution, I must insist that you make one of the six images in the pack available in full for free, so that people can at least be sure of the quality of the product they're receiving.
A piece of art with some flaws, mainly in how the author asks you to pay for it, but with some craftsmanship shown. I am sure that with time the author could be one of the best.