Well, I've got some characters from one series (or set of series) who can fill both categories.
Overglorified: Kira Yamato (Gundam Seed, Seed Destiny).
Now Kira in his own right is a capable pilot, but for some reason he has gotten a reputation about him of basically being unbeatable. Freedom Gundam and Strike Freedom Gundam also pretty much make battles very easy for the guy. When all he had was the Strike Gundam, we actually saw his skills at work. Basically he gets way too much praise for basically being a Boring Invincible Hero (as the tropes go)
Disrespected: Shinn Asuka (Gundam Seed Destiny)
Essentially the Kamille Bidan to Kira's Amuro Ray. Shinn is a mentally anguished pilot (having witnessed his entire family get killed in a battle during the events of Gundam Seed), but he is also greatly skilled. In fact, using only the Impulse Gundam (which was more or less a beefed-up clone of the Strike) he managed to actually defeat Kira and destroy Freedom Gundam. With his Destiny Gundam he was a force to be reckoned with. Unfortunately he suddenly becomes the bad guy after his superior shows his true colors and in the final battle his Gundam is torn apart by Infinite Justice Gundam and Athrun Zala. He pretty much goes from Hero to nothing in the blink of an eye. A lot of fans were not pleased.
Also disrespected: Cagalli Yula Athha (Gundam Seed/Seed Destiny)
The twin sister of Kira Yamato. In Gundam Seed, she was a fierce and determined individual and a strong pilot, even managing to become the only regular human to achieve the Seed Mode state that Kira, Athrun, Shinn, and Lacus Clyne are normally only known to possess. In Gundam Seed Destiny, however, she became almost solely a damsel in distress, unsure of what she should do. Her only moment of glory was the first deployment of the powerful Akatsuki mobile suit, which she would then give to another character and basically disappear for the rest of the series. Not only did the fans not enjoy this derailment, her seiyuu Naomi Shindo refuses to play the role anymore (even in the video games).
Actually, when Gundam Seed Destiny was dubbed, everyone involved apparently weren't too happy with the series. That really says something about the writing in that series.