It's not horrible. Really. It's just that there are much better shows out there that do the same thing. The Tinkerbell movies do a very good job creating its own lore and characters full of whimsy and wonder. My little pony does this as well. But this simply takes elements from both shows and combines them into a semi-regularly airing show. Do you want fairies? You got it. Do you want unicorns? You got it. Do you want magic and a fantasy world? Done. This show does add something else though. Instead of just taking place in a fantasy land, a non-cg girl travels from the real world to the world of Mia and me when beckoned.
It fills the gap while better shows aren't airing.