Yeah, I have to agree, he brings nothing new to the table and we already get a druid companion ( that I mostly prefer over him). He starts hitting on you as soon as he becomes a companion and that's it.
I think, they should have kept Helia as companion instead.
To me, Halsin has become a meme character ( and not in a good way) and it seems, most of his fans are unhappy with the romance anyway.
They have worked for Helia for a few years judging by when Chubblot first showed her datamined content, Halsin on the other hand is the one companion, that lacks debth ( can't say much about Minthara, since I don't go down that route).
I'm kind of sorry for the Halsin fans tbh. They were so hyped. Since Helia isn't an option anymore, I hope, they at least fix Halsin up for his fans. In my playthroughs he will be mostly staying in camp because, come on, Jaheira. I nearly fangirled about her as much as Karlach.