Hey, i am trying to get some poison skills as well. So far one Skyrim-Overall-Thing can be said: No matter what playstile or skills you choose, you will become a beast.
But about the Alchemy, i guess it really has its place. I think for me, Alchemy just replaces Magics in its manners. I just begun with brewing some poisons. (try and error, eating ingredients, buying recipes.) I came up with two very useful poisons, 1 stopping all magicka regeneration for 33 sek (which is especially good against mages and their annoying frost stuns), the other slowing down enemies by 50% (but you could use a shout, or the steady hand perk...) But poisons like Fury (attacking everyone around), Paralyzing completely (no movement) can become very tough. Sure my brewed poisons can be improved a lot.
this might not answer your question properly. But may give some info..