I think it's cool in concept, but doesn't really work well in practice. Straight spellcasters get hit with a serious nerf stick. Sure, you can now cast fireballs and use cure serious wounds... but your 5th level fireball now does 3d6 with a range of 30' with a 20' radius. This is what we in the business call "teh suck". And don't get me started on mage armor that causes spell failure.
I like the way things are broken down into their components and that players get to make whatever spells they want... but the balancing act just doesn't work out. The problem is that spells in D&D aren't linear in power. You can't say a 4th level spell is twice as powerful as a 2nd level spell... it's probably more like 3 times. With 4th to 8th, it's even more pronounced, maybe like 4 times as powerful. But you can't get that with their linear system.
Do you have Arcana Unearthed? It has a really cool spell system that is significantly different from standard D&D, but close enough to remain balanced with it. If you don't have it, I have a copy I don't need anymore (got Arcana Evolved a couple weeks ago).
-The Souljourner