While I voted useful and well-characterized, I also think his fights have become rather anti-climatic. The only time he received a serious injury in a fight was against the Female Titan, and he got it saving Mikasa. After seeing him experience only victories with little to no damage and cost done to him, his fights aren't as riveting as they first were. I mean, his overpowered theme has been taken a step too far in my opinion, and it's gotten dull.
Honestly I disagree. clearly I appreciate levi especially for his character and his well articulated personality, but also the fights know how to be interesting. In my opinionhis fight always left you with bated breath ... for example in the first fight with zeke, I thought zeke, being the strongest warrior, and therefore the counterpart of levi, would have been the only one able to beat it. Also when he fought with the remaining 40 titans I was convinced he couldn't do it
In the second clash I thought that since the titans that he faced were his companions and zeke had prepared for the fight, I had serious doubts that he would win. So in a nutshell I always found the battlefields very exciting, because every time the probability that he died would increase. Moreover there are 3 levi combats in the end, so I don't understand how boring they can be.