I've just started (in the last month) on EM 10g and Quest Spotlight. The site I'm at uses both. I usually use TOAD'S session browser just to give me an easy formatted view of what's running and if there are any problems I run scripts and investigate. My first impressions are "Death By Information". There is just so much minutae about the database I can handle. Alerts popping up all over the place about some arcane metric. Then I have to spend my time on how to shutoff the metrics. Having always concentrated on the database side, I find the three ORACLE_HOMES, configuring of OMS and agents, hard on my head. But I guess I should have a rudimentary grasp. I guess I'm just bitter from always getting pages of meaningless printouts showing "all green lights" from SA's when I complain about slow disks.
-- //www.freelists.org/webpage/oracle-l