Right from the bat I just want to say that I love watching Robert Davi as a bad guy. He's simply cool to watch. This episode reminded me of season 1 of Atlantis and the early years of sg1. McKay finds a device in the ocean while sheppard encounters Koyla again. Meanwhile Woolsey has a smitten relationship with a new member, Vannessa.
Without giving anything away, the story seems flawed and messy but it all intertwines very nicely at the end. And for me that's what a good mystery does, by placing all the pieces of the puzzle together = giving you a nice fuzzy feeling. I liked the ending when we saw the true nature of the beings. Overall, a classic Stargate episode. I tip my hat to you good sirs and madams.