The log-adjacency-changes OSPF configuration command was improved with the detail command that logs every step of OSPF adjacency establishment (sample printout below), making it a great troubleshooting tool.

%OSPF-5-ADJCHG: Process 1, Nbr 172.16.0.21 on Serial0/0/0.100 from DOWN to INIT, Received Hello
%OSPF-5-ADJCHG: Process 1, Nbr 172.16.0.21 on Serial0/0/0.100 from INIT to 2WAY, 2-Way Received
%OSPF-5-ADJCHG: Process 1, Nbr 172.16.0.21 on Serial0/0/0.100 from 2WAY to EXSTART, AdjOK?
%OSPF-5-ADJCHG: Process 1, Nbr 172.16.0.21 on Serial0/0/0.100 from EXSTART to EXCHANGE, Negotiation Done
%OSPF-5-ADJCHG: Process 1, Nbr 172.16.0.21 on Serial0/0/0.100 from EXCHANGE to LOADING, Exchange Done
%OSPF-5-ADJCHG: Process 1, Nbr 172.16.0.21 on Serial0/0/0.100 from LOADING to FULL, Loading Done