Quick overview of Pinhead (Before Crash Fixes)
I've been trying to play Pinhead recently and estimate that I've had around 30 or so completed games with him. And I've gotten both of his achievements.
But even despite that I feel that I still haven't quite got the experience to fully talk about him because of how many of my games kept resulting in a crash. But here's a summary of what I think so far
Possessed chains
They're honestly a pretty good chasing tool. If all 3 chains land then you can get some really nice distance on the survivor. It's a bit unreliable on indoor maps because of all the clutter. But the Impaling Wire add-on neatly takes care of that. I've gotten a decent grasp of how to use them and once I stopped missing so much they really started pulling their weight in matches.
lament configuration
There's only 2 ways the box interacts in any game. Either the survivors are too far way to interrupt when solving it so the most you can do is teleport or else let them finish. Or if you happen to be on a decently small map with add-ons to increase the solving time. So you can continuously harass and eventually down the box carrier for pressure on all survivors. Even more so if you can chain multiple downs in a row to keep the chain hunt going. Pinhead becomes really oppressive if he keeps getting his box.
add-ons
For once we have a killer who's most powerful add-ons are actually the rarest! Both his Iridescents are really good. The Impaling Wire is probably the best amongst his purple add-ons. But I do think that if you don't have at least 1 purple or rarer add-on equip that Pinhead suffers performance wise. He's add-on dependant.
I'll be writing a more cohesive guide once they fix the crash bugs.

Comments
Please do. In the meantime, I'd like to add what I've felt on how to use him. Granted, I have, uh, significantly less matches than you. Feel free to consider or discard them. I think if you just downed a survivor, it's worth teleporting (unless you know they're at a safe spot in the map). It's basically free slug pressure. I also think that his chain hunt speed add-ons are worth running as well. They put more pressure to solve the lament configuration, which might result in more passive slowdown.