I have moments (generally after dying after a long go, or when i have a surprise death in an easier level) where I have enough of it and just need a break. But I’m so far still coming back to it. I would like to complete it at least once though, although I don’t think I would end up going back to complete it at all of the harder difficulties afterwards, but who knows. It’s still really good value for money though, and I think the daily challenge is a great thing for longevity.
But yes, I would like a bit more storyline to it also. I like the little bits that you stumble across, although there probably won’t be enough to have any full in-depth history.