I'm also experiencing the same problem. I import my appliance, set the hostname and IP in the import wizard then turn it on and accept the EULA and set the SSO password. I then follow KB2057223 to replace the certificates and that's when I get the health alerts:
VMware vSphere Profile-driven Storage Service,Alert,04/12/2013 10:33,Unable to retrieve health data from http://localhost/sps/health.xml
VMware vCenter Storage Monitoring Service,Alert,04/12/2013 10:33,Unable to retrieve health data from http://localhost/sms/health.xml
Visiting the URL gives me the same "503 Service Unavailable" mentioned by fcardarelli.
Edit: I've followed this procedure twice with the same results.