After that we have Natsu somehoe just eating God Slayer flames, somehow becoming stronger then he should be. And lets not even get into the Sting and Rogue fight, where he single handidly warfed people who appeared to be the MAIN VILLIANS OF THE ARC. Basically, Natsu is everything wrong with the "super powered main character" archtype. He started off good, had some fantastic development with Gildartz, but then it was all thrown away.
I dont have a problem with the godslayer fight because if it had not been for Makarov Natsu would newer have gotten the time needet to finish off his meal, and instead be burned to ash.

I do agree on though that the Dragonslayer fight was awfull, and it came close to ruining the entire arc for me.