Pretty much agree with most you said. The visuals were overall excellent, only the Medusa looked a little 1999 to me. I also found the Kraken showdown to be a bit too short after the huge set up. And more Gods doing or saying more awesome stuff would have been nice. I liked Neeson as Zeus, though. But I was really entertained and had fun with all the monsters, landscapes and guys with burned firewood as a face.
A few times the film reminded me of the Mummy remake, and that's a good thing in my book.
It's true that 3D doesn't have much to add to the film, sadly we didn't have a choice in our region.

But I wonder, what is the Andromeda twist that surprised you so?