What's Gulden's unique selling point though? Is there anything BTC or one of the other major currencies can't do?
a few things come to mind.
check this out for a quick comparison:
https://dev.gulden.com/besides that.. Gulden is on a EUR - NLG exchange (nocks)
companies are accepting Gulden in Holland. Those may have not supported Bitcoin or any other crypto at first.
you can use Gulden to purchase at places that accept Bitcoin. Gulden will then automatically be exchanged to BTC. obviously that's not an advantage over BTC but it does bring an advantage over most other altcoins.
In fact most altcoins are quite useless compared to Gulden.