Well, he did cut off Vegeta's tail and effectivly end that Great Ape transformation which would have been imposible to efeat at the time. He also gives peeps senzu and helped during the Future Trunks Saga. But I do agree. He isn't the best character.
Yajirobe is ok to me, he knows what he does and does not want to do, yet he has the courage and the timing to masterfully jump into action when need be, in fact he was so good that Vegeta, Zamasu, and Black had no idea he was there when he cut off Vegetas tail, and when he saved Trunks. He's very, very good at sneaking around undetected.
Yeah. He does seem a bit prideful, (which he shouldn't) but then again, you see the peole he's up against. If he were just a plain out coward, it'd be different. He's like the early version of Hercule that way.
He defeated Cymbal, he also climbed Korin tower with Goku on his back on Goku's request where Goku could see Korin once more. He is prideful but he knows his limits and that's alright. Honestly he was never a big fighter. He only killed Cymbal because he was hungry and he only trained at Kami's because Kami requested.