You don't need me to tell you that Scions first sedan isn't actually THEIR first sedan, its a Mazda. Good, great and wonderful, moving on this is excellent news not just for product dry Scion, but for independent and cash poor Mazda.
While the styling is certainly a point of contention, the Scion brand has never had a distinct design language regardless, Mazda does build sporty and engaging cars to drive which squares with Scion brand mission.
Internally there's noting Toyota about this Scion. The iA uses Mazda's 1.5L 4 cylinder, good for 106 bhp, routed through a 5 speed manual or 6 speed automatic. Scion supposes the iA will pull down 42 mpg (highway probably but not specified).
Suspension is again decidedly Mazda, MAcPherson in the front, torsion beam in the rear...but the car weighs less than 2,500 lbs with either gear box. Rear brakes are drums, with no upgrade option. Complexity need not apply.
Scion will offer the iA in monospec for a digestible $16,000, whether that prooves a better buy then the Mazda proper is yet to be seen, but do expect a healthy selection of accessories in stores.