It seems useless most of the time. So many enemies are immune to poison. I spend so much time fighting Draugr that I can't seem to find alchemy worthwhile, but I would like to. Any suggestions?
I almost never use poisons. Generally, I carry 6 paralyze poisons to deal with big swarms, like Dustman's Cairn and the Silver Hand. Or when I try to get into Halted Stream Camp at a low level. Other than that I find I never remember to use them so why bother.
Nevetheless, alchemy is the route to making an OP character. With all five power perks plus benefactor (which is what I take), and wearing alchemy enchanted clothing I can make a fortify smithing potion that increases smithing 120%. This is without using
any fortify enchanting potions.
I can also make a potion the regenerates health 150% faster. Combine that with some regenerate health armor and you can survive ebony archer Deathlords rag-dolling you all over the place.
Invisibility potions also can come in handy for certain quests.
At low levels, even the wimpy health potions you can make can be a life saver since their never seems to be enough minor health potions. (note I play at master level, so I take a lot of damage.)
Alchemy is also a good way to make money.
If all you are thinking about is poisons, then yes, alchemy is pretty limited. But for other purposes alchemy is second only to enchanting for buffing up your combat abilities.