To be honest, as an adult player, I'm not only surprised at how hard this game is but also how expensive everything in the game is.
My two points kind of go hand in hand - simply put, the fact that every new addition to the game costs an extraordinary amount of money is unbelievable. Mr. Carrot Cake for 4500 bits? I cringe at what the rest of the mane six are going to cost. -_- Also (and yes, I realize there's an equation out there to getting the most bits out of your shops), getting bits is time consuming and frustrating, ESPECIALLY when you're just starting out. So far I only have six ponies, and five shops - I could put three ponies in the highest paying shop, but it would also take me days to build up enough bits to get the big stuff done. So I put one pony in every shop, and yes, it's less payout, but it's more instant gratification, since I don't have a lot of time to play.
Kids have the attention spans of caterpillars, you really think they're going to wait around for their highest paying store to deliver the payout? Nope. They want the satisfaction of completing something, and if it means a faster payout, they'll do it.
Because Gameloft has done this with other games I play with them, they will probably have a sale on bits/gems/etc. to entice people into buying them. So don't run for your credit card just yet - wait for the sale.
What really annoys me above all on these Gameloft games (not limited to Ponies) is the whole "get free stuff" option. You only have to sell your soul to get the free stuff. "Complete a quick action"? How about "Fork over your credit card, we'll get you one way or another!"
I haven't gotten to this point in the pony game, but again, in another GL game I've played, the ONLY way to advance will be to buy an item. I fully expect to run into the same issue with this game, because I assume that's how they operate across the board. I got turned off on the idea, but, with the sale on bits, it should bring the pain down a bit.
I would also like to note this (and I don't know if it's a bug or not): Don't touch the elements once you push back the darkness on them. I made the mistake of touching one and started losing the hot air balloon gems I'd gathered. I don't know where they go, I just know that I lose them. -_-