Heart of Kiran has very good stats and a couple
of possible niches. It's easily in consideration
for a top-tier role in vehicle-based decks, and
some of the dwarf pilots from Kaladesh can meet
its crew requirement using only one card. In
other creature-based decks, there are options
that don't require locking down other attackers
and provide similar speed, but it's not out of
the question since it gives you an attacker and
defender equivalent to midgame creatures with an
early-game converted mana cost. The fact that it
also invites use in a planeswalker-heavy deck is
interesting; most such decks don't really need
any help ending a game and don't need to attack
to do so, and as a defensive option for such
decks it doesn't offer the bonuses that Wall of
Omens or Wall of Reverence do. I'm also not sure
you always want to move your planeswalkers away
from their ultimate in such a scenario, but it
might be interesting to try out.
A fairly unique vehicle, Heart of Kiran is
basically Smuggler's Copter replacement,
slotting in at the same point on the curve. The
analogy isn’t perfect; this has a higher crew
cost, but it fights much better on both offense
and defense. The alternate crew cost is a cute
touch, but it's more an ancillary feature than
it is the main attraction.
A 4/4 with flying and vigilance is an excellent
stat line, and Crew 3 is doable by turn 3, after
you resolve a creature for the turn. I think
this is easily going to be the go-to vehicle for
the near and foreseeable future.