The key to the long term viability of any digital currency is acceptance from merchants. Obviously bitcoin leads the pack in this regard. Litecoin, PPcoin and Feathercoin will continue to lag behind until they can improve there standing with merchants.
Netcoin had done a tremendous job building up to its release. If it could get some merchants lined up in advance it would be an absolute winner. I currently accept bitcoin, litecoin and ppcoin at
DirectVoltage.com and plan to accept netcoin from the get go
Bright