i would like more gray levels because some of the art/crafts books i read could really use it. but for graphic novels/manga the screen and resolution aren't good enough anyway. i'll live.
i like the kobo because it does what i want a bare-bones ereader to do, it does it well enough, and at a price i could justify to myself. it's light enough to hold for long periods of time, i can take it with me anywhere, it's robust enough to survive falling off my bed, i LIKE the muted contrast of the e-INK screen, the page turn is fast enough, i don't seem to press a lot of buttons accidentally, it feels good in my hand, and it even looks good. the OS is linux -- the mere possibility for hackery always makes me happy, because if the manufacturer were to let us down, we can roll our own.
generally i like specialized gadgets over one-gizmo-does-it-all. if it fails (and they all do), i've only lost one function. i also don't like bloat -- wifi isn't necessary on my ereader because i manage my e-library on my computer anyway. one of my friends rhapsodizes about how cool it is that she can buy a book directly on her kindle while she's out lunching somewhere in manhattan -- more power to her, but i can wait til i get home.
the kobo is not my ideal e-reader; that one doesn't exist yet. it will have all sorts of bells and whistles; basically be a library and research tool, with online connecticity, search, highlighting, annotating, dictionary lookup, quote-collecting, etc.
that's not what i bought the kobo for. i bought it to replace my paperbacks. it's doing pretty well at that.