Well, why is he?
He has BOTH minor gods that benefit u on water maps:
GPs: Scout ur opp at around 4-5 min. docks built close enough together? go ards and use pestilence. docks spread in anticipation of pestilence? go athena and use restoration. both can help u win the water.
Myth Techs: What unit do u have resources for while fighting on water? hoplites. what myth techs are available under both minor gods? hoplites.
Myth Units: What resource do u have to spare for myth units during water battles? food. certainly not wood for centaurs. What resources do minotaurs and cyclops cost? food.
The one noticeable difference is the lack of the scylla in heroic. however, most water battles are decided in classical and medit is the only map where u really want to fight to retake the water in heroic. anatolia has lots of hunting and gold in the middle of the map and midgard u don't have to play it as a water map at all if u don't want to.
Now, I'm not saying Hades is as good as the norse or eggy on water, cuz he's far from it. However, I'd say Hades is at least as good as Zeus. The one difference being that Zeus can bolt the opp's dock-builder 50% of the time, thus slowing the opp's econ slightly. However, even this is next to impossible on medit if the opp starts building the dock immediately.
I think Hades is just a Greek and Greek's are the worst on water; plus Hades can't fight to reclaim the water in heroic like Possy or Zeus can.
But is that enough to make Hades the worst? I dunno. Classical is the time when the fighting is most important and I think Hades is better off than Possy or Zeus in terms of having two flexible minor god choices. But, of course, Possy does have the cheaper stables and cheaper hippikons, so maybe that makes him better.
Any thoughts appreciated.
fh