It appears this flying Merfolk creature will be a force to be reckoned with in all blue decks this season. Thieving Skydiver can easily steal an opponent's Stonecoil Serpent for a mere 3 mana, though you will still need to pay 1 mana for the kicker effect, even if Serpent Coil technically costs 0 mana.
Aside from that, there are plenty of artifacts that can be used alongside this card in competitive decks.
Thieving Skydiver is not on par with Agent of Treachery, a card that can steal any permanent card in your opponent's control, but it doesn't mean that it won't be loathed by the community for similar reasons. Especially, when the stolen artifact acts as an equipment card.