I don't think they gave us a slap. I really enjoy the 5 inch screen of the Butterfly and I won't switch to a HTC One even if someone offered me one. The only thing worth noting is that bigger battery, it should have much better battery life compared to the Butterfly as it has a bigger battery and smaller screen. Even though the Snapdragon 600 is faster, when do you actually need that speed? Jelly Bean and the S4 Pro is already extremely snappy.
The thing that worries me is the dev team though. I am sure devs would go to the newer One but I really hope our Butterfly gets a good dev team.