One point of interest in Twisted Image is that not only does it switch the power and toughness of a creature, but it also draws you a card. For one mana, that’s a pretty good deal. Even if you’re casting it just to draw the extra card, it’s worth it. In infect, it also puts another card in the graveyard to help you delve for Become Immense or draw you yet another pump spell. Also, with the Enchantment Wild Defiance on the board, you turn Twisted Image into yet another pump spell. Wild Defiance gives any creature targeted by an instant or sorcery spell +3/+3 until end of turn.
Another interaction that’s come into play since the release of Oath of the Gatewatch is Twisted Image’s interaction with Stormchaser Mage. The Prowess creature begins life as a 1 / 3. Not only does Twisted Image activate Prowess and draw you a card, but essentially gives your Stormchaser Mage +2/-2. Whether Prowess aggro decks, either red/blue (Izzet) or red/blue/green (Temur) actually become a strong force in the format will go a long way in determining the future value of this instant.
With Slip Through Space already breaking into the Modern Infect deck as a one-mana cantrip that makes a creature unblockable, it remains to be seen if the one or two copies of Twisted Image in the mainboard is worth it.