I bought this for my daughter's winter dance recital. Based on previous reviews, I bought one in her size and the size up. I had her try on the smaller size and she complained that she could not stand up straight! Tried on the larger size and it fit fine. So, other reviewers are correct in stating that this one runs small. Otherwise, it appears fine from what I can tell as she won't be wearing it for another month.
I gave it a 4 because of the fit. My daughter wears a 4T and ordered size C which is a 4-6 and it fit very snug and didn't give her much room length wise. But I love the style of this one compared to the pinch front that my other daughter has to wear.
I ordered the 4/6 for my daughter who wears a 5T and is starting to get into 6's. This was very small. Fortunately, I also have a 2 1/2 year old who wears a 3, that I gave the leotard to her. Overall though, I recommend.