Oh, and where can I find some empty flask for potions anyway?
Youｴll find empty falsks where you expect them - in the boards, cupboards etc. of anything and anyone connected to alchemy. Just one example would be Evelyns hidden lab in Cyseal.
As I tend to be a hoarder Jahan in Hunters Edge already has gathered roughly 80 empty flasks. But I admit that means going to everything that just might contain something.
For not being worth it - crafting weapons is definitely worth it, crafting and filling spell books is definitely worth it, crafting special arrows is definitely worth it. Crafting rings and belts before you find decent stuff, so between levels 4 and 7, is definitely worth it. Giving a glass cannon mage a +2 constitution belt (you canｴt find something like that) is definitely worth it.
And if you look at the value of the "5star dinner" talent - doubles foodstuff effects - well, that for the thingie called "dinner" means 156 health, 2 strength. Makes an absolutely low rated talent worthwhile suddenly as well as crafting food. Or better said it would do it if the devs would not have literally flooded DOS with way too many health potions.