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.
Gulden initially seemed like one of those strange "national" cryptos that just sprouted up over the years and were trading for volatile values before just dying out. But if you start to look like I did, it does seem to stand out exactly for that reason above: merchants and companies accepting them as payment. On this alone, adoption, is Gulden special from other national cryptos.
I still do not know much or enough to buy Gulden (since I am not in Holland anyway). And I think you have to understand the other Gulden competitor, which I do not at all!