"Good flash /so far/, why the bad ratings?"
...Oh, that is why" was my reaction to that finale.
The flash itself is pretty well done, but the punchline of the flash was sophomoric at best. I was waiting for the end to see what unexpected hilarity took place (the whole mock seriousness of the flash itself was leading up to it) and that's an effective humor tool...and even though I wasn't expecting that ending, it wasn't in a good way.
I think there's a lot more material out there that's really witty and genius you could've come up with if you put more time into than Zeus defecating on Kratos. That sort of humor is just an easy way out and it'd only work for a very, very young and immature audience-- an audience that probably has little to no appreciation for the mythology involved in the flash-- and that's where this flash went awry.
If you would've consider your intended audience here better, I think this flash could've been worth much more than it is. It just ended on a really poor note and it ruined an otherwise decent flash.