Sure, but as I think was discussed on the ATP podcast, it was probably a marketing gaffe more than anything. If they had called it "Monument Valley 2" and charged the same, people probably wouldn't have complained too much, as that sort of branding is more in line with App Store expectations. (Maybe not, though.)

In any case, whining aside, I doubt their sales suffered too much! And I'm glad we're getting more high profile pay-up-front games like MV to reset buyers' expectations.