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.
All wallets are HD, desktop wallet uses new account system for privacy. You can also link your mobile wallets to your desktop wallets so you can control all your funds from within the desktop wallet. There is also other things I can't think off the top of my head but the marketing of what Gulden offers is non existent which is a blessing in disguise or the price would be much much much higher.
However the big differences are coming in the next release with PoW2 (Witnessing) and SegSig (58% saving on transactions = more transactions per block and smaller blockchain)