EC2 Does have SLAs - http://aws.amazon.com/ec2-sla/

Security: Amazon does not makes any guarantee as to whom it will disclose your data

Please look at the Security and Data privacy section of the agreement - http://aws.amazon.com/agreement/

Persistence: ensuring persistence of your data (that includes, effort to set up the system) is complicated over EC2

Not sure what this pertains to. Ephemeral storage ? Permanent storage being backed up to S3 ?

Management: there are very few integrated management tools for a cloud deployed on EC2

Amazon's web management tool for EC2 is pretty good. Netflix open sourced their tool Asgard which does precisely what this - https://github.com/Netflix/asgard. Perhaps Asgard was not available at the time this comment was made.

The comments on Network and Cost still hold good. Network IO latency can affect throughput severely and cost is not a great win in the long run.

Why would you single out EC2 if you were looking at `Cloud computing` ? The question can be broader in nature even though the OP expressed interest in EC2 specifically.