The Elemental is a 3/5 flyer for 4U. Whenever it attacks, you tap all creatures the defending player controls. That's a pretty sweet ability, actually, helping you to swing past big problem creatures. Since Sultai decks play huge creatures like Tasigur, the Golden Fang, Gurmag Angler, and Sidisi, Undead Vizier already, that tap ability can be a game-ender.
Then, if you happen to need to Delve it away, you can pay 3BB, 3GG, or 3BG to return it to play from exile tapped. It does have to be played as a sorcery, which is kind of too bad. Having to be played from exile at sorcery speed is probably why this hasn't seen more play in that Whip deck. It's basically been relegated to the sideboard in a lot of build to deal with Aggro strategies, but some players have mainboarded it with some success.
The big thing about Torrent Elemental is that it can survive Languish, the new -4/-4 boardwipe in Magic Origins. It's really not a bad creature at all, and it seems playable. But now there will be no Whip to bring it back from the grave.
What should be noted is that you can get about 50-75 cents on buylist for the Elemental while they're selling for roughly a dollar at retail. You could probably get these as throw-ins in trade and hold them until rotation and see what happens. Most mythics buylist for about 50 cents anyway, so there's really little to lose on this card if you're just holding onto a few.