I think the paragraph that says RPKI is complex and deployment has been slow is a lie, quite frankly.
The five Regional Internet Registries (RIRs) have been heavily involved in the RPKI system, because they are the authoritative source on who the legitimate holder of a certain IP address block is. They launched a service to facilitate RPKI on January 1st, 2011 and adoption has been incredibly good for such a cutting edge technology (for example compared to IPv6 and DNSSEC). Since the launch, more than 1500 ISPs and large organizations world-wide have opted-in to the system and requested a resource certificate. The service that the RIRs offer, along with several open source packages by third parties for management, ensure that network operators only have to worry about entering data and not any of the crypto, making it robust and easy to use.
With their certificate, an ISP can make a validatable claim – known as a Route Origin Authorisation (ROA) – about their prefixes, stating "As the holder of these IP prefixes, I authorize this Autonomous System to originate them". There are over 800 ROAs in the global system, describing more than 2000 prefixes ranging from
/10s, totaling to almost 80 million IPv4 addresses. All in all, RPKI has really good traction and with native router support in Cisco, Juniper and Quagga, this is only getting better.
Global deployment statistics can be found here: http://certification-stats.ripe.net/