I certainly use self-hypnosis a lot and it can help quite a bit, mainly visualisation methods.

While I agree that all hypnosis is self-hypnosis to some extent, I also believe that being hypnotised by someone else is more effective in some cases. I've even found this for myself, there is a few times I have seeked someone to hypnotise me even though I am a hypnotist myself, mainly because I find it works better that way.
The way I see it, even though you can clear your mind, enter a trance and bypass your own conscious mind, you cannot take yourself through certain processes that a hypnotist can take you through effectively. For instance, I find 'authoritative' suggestions work well with me rather than visualisation methods, especially after conscious disassociation, addressing the subconscious directly and separately. This does not work well for me through self-hypnosis, as explained below.

I cannot achieve the same authoritative style with conscious disassociation in self-hypnosis effectively, because as soon as I start trying to give myself those direct authoritative suggestions, my critical faculty jumps right back in and starts to pass judgement on them, and thus the suggestions won't take.

I can take myself through self-hypnosis using visualisation methods quite easily, but I just seem to respond better with an authoritative style hypnotic process.