I've been playing around with the mod recently. I don't think it's broken at all. You need to be extra careful when you start making items from stored Essentia, because that can end up with things blowing up if you don't have a way of dealing with the buildup of bad stuff. Which is expensive to do. To me, that's not really the focus of the mod, though.
The spells, THE SPELLS, man. Why use bonemeal ever again? Use Growth to grow all your crops, and it's tiered to work in multiple x/y squares in diminished, normal and augmented modes. Fighting becomes fun again, as you can shoot bolts of arcane energy, burn your enemy, shoot slashing wind, teleport mobs around, levitate them... Portal Gun? Nope, at least not for going back to your base, Mark & Recall got you covered. Instant teleportation, with a reasonable mana cost. Burning in lava in the Nether? Getting bashed by the Enderdragon or Enderman in the End? Two spells that teleport you back to your bed in case of emergency from those two dimensions. Pickaxe? Why? The Dig spell is amazing. It's a mining laser that works off of Mana instead of EU, so you don't need to carry a Lappack around. Speaking of which, Quantum Armor just got competition, because there are multiple Shield spells that grant you temporary invulnerability or damage reduction. Summoning Minions! Specially the Shadow, which is another You. No need to carry buckets anymore, because you can now summon water. And lava, too. You can also make them vanish with your mind.
And what's best? You can combine spells. You can combine effects to create your own spells, so it's basically unlimited options. The worldgen it adds is pretty nonintrusive, there's only one ore added, Vinteum Ore, and the structures that generate are beautiful and populate the ever boring landscape. And it's actually pretty balanced, in my opinion. It's actualy pretty hard to get levels past a certain point, because you actually need to spend your mage level in minecraft levels to advance another mage level, so it gets really, really hard after a while to level up again, even using automatic XP farms.