She stole Link's horse!
This is probably the most used used of the bunch. Being an Ilia fan, I can assure you that I am highly aware of her fondness for Epona, but horse thieving? I don't think so. Ilia never stole Epona. She took her to the spring for healing. This makes her a horse theif how, exactly? Yes, she was upset... I don't recall saying Ilia was perfect or flawless. ...But I think flaws make a character more realistic.
She cares for Epona more than anyone else!
Anyone who says this probably didn't pay much attention to Ilia. We see Ilia take Epona to the spring (for healing) since she believed Link was merely jumping sharp fences to show off. However, once she learned Talo was in danger her supposedly overwhelming concern for the horse ceased to exist and was immediately focused on Talo and Link. The next (and final) time is in Kakariko when she commented that Link would never ask too much of Epona. These are the only times Ilia mentions Epona in the entire story. She did make the horse charm, but that was a present for Link so he wouldn't have to wander all over creation looking for grass whistles. Yes, Ilia does love and care for Epona, much like how someone loves and cares for their pet, but she does not pride the horse over human life.
She's just a selfish brat!
Seriously, Ilia is probably one of the least selfish people in the entire game. Yes, she overreacted in the beginning... which more than likely stemmed from her own sadness and worry over Link leaving Ordon for the very first time in his life (the previous situation with Talo probably doesn't ease her feelings). This is easily confirmed when she tells him to "come home safely."
She gives you such a useless item!
Yeah, the horse charm is pretty much useless considering you can warp everywhere at this point. Still, it's sweet and endearing that Ilia made it especially for Link.
She's so ugly!
Well, beauty is in the eye of the beholder...
She's too stupid to remember Link!
Anyone who says this might as well call a real person with amnesia stupid for not remembering. I know the amnesia plots are considered cliche, but so are random characters turning out to be Zelda.
All the criticism aimed at Ilia is easily explained away if you actually take the time to look into her character. While Ilia's role is not as prominant as Zelda's or Midna's she is an important part of the game and an important person in Link's life.