Hades is below the level of a deity of Zeus' authority.
Hades can be harmed by other deities, as shown when a fully empowered Hercules managed to knock him into the River Styx.
Hades is not omniscient nor omnipresent, as he has often called on the help of the Fates to determine the future.
it has been shown that Hades is bound by certain rules in regards to contracts made with others, such as the fact Hercules regained his demigod abilities after Meg was harmed due to it violating his previous contract.
Hades is often arrogant and ill-tempered, further limiting his power as he under-estimates his opponents and often flies into a rage when things do not go his way rather than seek out more constructive solutions.
