This was on no way on the level of Legend of the Legendary Heroes. While the anime did drag its feet during the wall invasion for no reason (happened pretty fast in the manga), the story progressed along quite smoothly after that point, as opposed to Legendary Heroes where it couldn't quite figure out where it was going and what it wanted to do. I don't even know how you see them repeating the same thing over and over again or your point about the characters.
The anime wasn't amazing but it isn't as bad as you make it out to be. If anything, it is mediocre to above average.
As Buff said, it was overall just fun to watch.