I am currently rating every DP outfit, and here are the ones that aren't exactly magical. (Please note this doesn't include what they wore when they were little. It also doesn't include Elsa or Anna.)
Here we go!
Merida's Formal Outfit

No wonder Merida ripped this outfit- it hides her beautiful hair, and it seems like she can barely move in it.

Cinderella's Pink Ballgown

This dress is what happens when you ask critters living in your house to style a dress for you- an atrocity!

Ariel's Rag Dress

This is one of those outfits that sorta make you ask, "Is this a joke???" At least they weren't showing her in the nude, I guess.

Cinderella's Nightgown

Blah. Just blah. Nothing special here.

Mulan's Father's Armor

I know she was pretending to be a man, but this look for Mulan isn't a glamorous one.

Mulan's Training Outfit

This seems more comfortable, at least, but still not a good look, even for a guy.

Jasmine's Peasant Outfit

Well, she wanted to look un-glamorous. She did that right.

Ariel's Pink Gown

The pink in this poofy dress does not go well with her beautiful hair. And that design just does not sit well with me. HellooOOO huge sleeves!

Rapunzel's Main Dress

This seems comfortable for Rapunzel's many activities in her castle, but the amount of pattern and color clashing going on here is unbelievable.

Ariel's Wedding Dress

I honestly feel that this would be a wonderful wedding gown if it weren't for those horrendous sleeves! Disney, if you're going to make your princesses so skinny, you can't overpower them in their outfits.

Rapunzel's Pink Dress

Rapunzel kinda has a pattern and color problem. It seems better than her regular dress, but this still is very unmemorable.

Tiana's Maid Uniform

This maid uniform kinda depresses me. It's a nice color, but they could have made this much cuter.

Tiana's Costume

It appears as though Tiana wants to dress as some sort of fairytale maiden, but that is not a good color on her... just saying.

Belle's Green Dress

Of all Belle's monochrome dresses, this is probably the worst. It's just kinda boring and does nothing for her.

Jasmine's Red Outfit

Uh, red is a nice color on her, but honestly, the meaning of this outfit is a little upsetting, if you think about it... Jafar made her wear that outfit as a SLAVE.

Mulan's Matchmaker Outfit

This comically over-the-top outfit had a lot of clashing items and did not match Mulan's personality at all.

Mulan's War Pajamas

Nothing glamorous to see here. I guess you can't have cute pajamas when you're pretending to be a man at war.

Jasmine's Wedding Dress

This dress is... okay, but it seems a little bit space-y, don't you think?

Tiana's Orange Outfit

As far as work outfits go, this shirt isn't so bad. The way she rolls up the sleeves is pretty cool. But really.... it's orange!!

Jasmine's Purple Harem Pants Outfit

This is a pretty color, but the gauzy wrap thing really overpowers Jasmine's tiny frame. Sorry, Jaz, but there could have been other ways to pull that off!

To be continued in Part 2: Middle and Higher Ranks!