Kaladesh's Gearhulks are this season's
equivalent of M11's Titans, and I don't doubt
they'll be controversial to some people. If
you've been playing as long as I have, you may
still have trouble associating expensive
creatures with comes-into-play abilities - what
do you need all those triggers for if you have a
5/4 with menace? Something like Noxious Gearhulk
won't quite take over a game the way Grave Titan
does; it gives you a momentary advantage and
provides you with something to build offense or
defense with, which is more than enough for most
players. It's also a really good trump card if
your opponent also has a Gearhulk already!
A 5/4 with menace is not very well-costed at 6
mana, the lower toughness leaves it vulnerable
to some of the more powerful burn spells. What
makes this better is that it's a kill spell
stapled to a 5/4, and you can pick off a
menacing creature so this one can menace the
crap out of your opponents.
Noxious Gearhulk is better than it looks, but
I'm unsure of how good it actually is. The sum
of the package is, indeed, greater than the
individual parts to the package, and I can see
this having an impact in Standard throughout its
life. Because, even if this guy gets killed
instantly, you still spent 6 mana ideally to
snipe a troubling creature and gain a reasonable
amount of life in the process, and there are
worse things to do with 6 mana.