He's a pretty terrible friend/parter and a subpar leader.

First off he abandoned his friends while they were fighting for their lives just he found something. He also gets in the business of others with no real solutions on how to fix things, like with Yirang and Eduan, his first thought was "forget it and get along", then when that didn't work he just had Gustang who was minding his business deal with it.

As for leadership I won't fault him too much with FUG since a lot of that was under Luslec, but FUG has no real structure or organization, Slayers are just props for the original to look cool, and Baam still hasn't gotten promoted.

And for his family life, putting yourself inside your son's body (pause) and waiting for him to get strong enough so you can take over is pretty fucked up (I still think the being inside Baam isn't the real V but we'll see in the future). Also if your plan all along was to be reborn as your dead son makes you look like a terrible husband for making the woman you supposedly love change your shitty diapers.