I prefer Dogmatic headcollars as they do not ride up into the eyes as Haltis can. They do need to be used correctly to be effective, there is nothing a dog can't pull into if it really wants to so they are not a magic cure. However, they will give you power steering should you need it.
With any headcollar you should ensure it fits properly, use a lightweight double ended lead with the other end on a normal collar, and not give sharp or strong corrections - aim for the minimum. You should also introduce the headcollar before using it by putting it on the dog without the lead and rewarding the dog when the headcollar is ignored.
Obviously a headcollar should only ever be used with a short fixed lead, not with a long-line or extender... obvious, yet we met a Dalmation last summer which had a headcollar attached to an extender lead. How the dog didn't have a broken neck I don't know.