I love my Kobo mini. I bought it for the ultra portability benefit and was so impressed that I went out the next day and hunted down a Kobo glo so I could synch my highlights and notes.
I am coming from several years of e-reading: kindle keyboard, kindle fire, kindle paperwhite.
Besides the portability I really enjoy being able to manipulate the font weight and the line and margin spacing.
But the Kobo feature I am most thankful for is the chapter page number - knowing that gives me a sense of where I am in the book and that for me is a comfort..
I have not used the glo enough yet to fully compare it to the Kindle paperwhite, but I will do that once I have a couple more books under the hood.
In the meantime the mini is with me constantly, I just shove it into my back pocket and go. I no longer sweat out a long line at the bank..