My 2cents: In one year of use i've never encountered bugs or problems (but, I use sideloaded kepubs only and wifi always off so it doesn't upgrade) and never had to reset, log out or even turn it off. I'm extremely happy with my Kobo (and the amazing plugins those here at mr have created), it is perfect for me and I have no complaints (for now
) Setting it up was very easy and reading is pleasant, nothing distracts me because everything works just fine.
So, i guess it's also a bit of luck and the different ways we use them ...