I was actually referring to the actual price ($80) and the introductory price ($50). Remember Coda 2? Everyone with Coda 1 had to pay 50% off to upgrade. "Half" is a common upgrade price, 62.5% isn't. This example may not convince you, but I'm sure you can find others more fit.
Weeks before the release they had to reply tweets regarding if it would be a paid upgrade and they said "they would only know in the release". This bothered me the most, we could all be told previously that it would be a paid upgrade at least.
Also, their reply doesn't sound like they had a solid business strategy at all.
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Of course, I already bought Sketch 3, it doesn't mean I can't be frustrated by how they handled the whole thing. I just hope they learn the lesson for Sketch 4.