As long as the gameplay is there, I think HWN will be just fine. As I mentioned, I too am in the camp that at the moment I actually prefer the aesthetics of UMN, but that could change as more is shown on both games.
Were both games rulesets/coding being done by the same person? Was there formal template they followed and just substituted subject matter? Are they completely different play wise in modes and rules? These are the things that will ultimately make a difference. (if anyone knows the answers feel free to speak up).
I think artistically where I am having trouble with HWN is way too much orange. I get it...Halloween colors, but Halloween is also lots of black, and this pin looks more thanksgiving than halloween in my mind. Too bright. Too cheery (even with knives and blood spots all over it). I get it...but it just isn't ringing with me yet.