I have been a Kobo user for long (I don't remember how much but I think that more than four years). I've got frozen devices, restart, problems with FW... but I expect it as I've lived a lot of time with my computer
Can I read in it? Yes. Does it behave mostly as I like? Yes. Then I'm good with it. Doesn't KA1 so much battery as my Aura? No. But to have to charge it once in a fortnight (as I only read in it by nigh, Aura is my on-go device)? It is not a burden for me. Gradient? Green spots? Sorry, not a lot of influence (I don't really know if I have). Automatic adjust? It has been worse with the last FW, yes, so I've reached the same decision than intelligent buildings and automatic-driven cars: out.
Am I go to complain about the faults? No. Am I happy with it? I am, perhaps other wouldn't but I like it.