What those folks fail to realize is that the original Niv-Mizzet basically NEVER attacked. At 4/4, he often wasn't big enough to attack safely, and furthermore, he has that sweet, sweet Tap ability, so even if you could attack, usually you'd rather just draw a card.
This incarnation fixes that problem. He's bigger, making him more combat-worthy, and his ability is no longer a Tap ability so you need not choose between attacking and drawing a card. You can do both. In fact, this version strongly encourages attacking!
The only downside is that at least the original design was a little more "build around me". Had that cool interaction with Wheel of Fortune effects.
Now is also a good time to bring up the interaction between Overload and Horobi, Death's Wail. Horobi + Blustersquall = Destroy every creature you don't control for 3U. Just throwin' that out there...
This should easily approach Rite of Replication, Bribery and Consecrated Sphinx levels of ubiquity.
EDIT: By now, it's pretty much tradition that I go full retard on one card from a set review. This time I completely blanked on how Overload worked... I was thinking the Overloaded version was a 5-mana Shatterstorm, which would be pretty "meh". But obviously, as this will never touch YOUR artifacts, it is sooooo much better than that. In artifact-heavy metas, this should rate pretty highly.
Let's get this straight right now. You can't just throw this into any old deck with the right colors. You really need to be pushing the Instant and Sorcery count way up, and minimize the number of permanents this could whiff on.
It's easier to build a deck with all permanents than one with none, so this requires a lot more finesse than Genesis Wave.
But, if you build around this, and manage to cast it for a high enough X value, it WILL win games. It is exceptionally powerful, of that there can be no doubt. Will doubtless inspire more than a few deck ideas.
Four mana countermagic better be pretty damned awesome to see play in EDH. This is no Mystic Snake or Cryptic Command, but I think it stands a reasonable chance of being playable. Countering a giant threat is always good. Adding some damage in for extra value is just gravy.
I still want a foil copy though... DAT ART!
Remember that theoretical "Instants and Sorceries matter" deck that will inevitably designed to break Epic Experiment? It'll definitely be running this guy. Yeah, he's a little creature, and thus not likely to stick around long, but he does a great job of speeding up your game plan while he does stick.
Very playable, but not very reliable. I think that perfectly captures the Izzet flavor.
This guy is a bomb. He might not look like much, but he provides very cheap, repeatable card draw, or cheap, repeatable removal. Anything that lets you draw two cards for U is worth a look. Hate all you want, but I'll be over here playing the shit out of this guy.
Seriously, this guy is the shit.
Definitely not meant for EDH play. Terrible, even.