One of the best characters to have been introduced in the show. I wish there was more of him in the show. But since he's too powerful they couldn't have him much in the show. If he was there half of the friendship speeches wouldn't happen and fights wouldn't be cliched. I think only 2 characters are more powerful than him: Zeref (Till Natsu beat him with the power of cliched MC) and Acnologia(Also beat as if he were a beginner towards the end of Manga).
He is powerful enough to be able to cast the three Grand Fairy Spells. Why is not a wizard saint again? He could beat all four of them without breaking a sweat. There is certainly no soul in Magnolia stronger than him. He is definitely the strongest human.
He survived a one-on-one battle against Acnologia (lost an arm and leg, still the strongest human) inspite of not knowing Dragon Slaying magic.
Grand Magic Games would've been over in few minutes if he were part of it. I mean he'd make FT the #1 guild again in no time.
The relief on everyone's face when they see Gildarts enter the battlefield (Tenrou and Alvarez arcs) says in volumes of his strength. Everyone looks upto him. He needs no friendship speech to win a battle.