One problem I have with the Scion rules is that it's even easier to to make an ineffectual character than it is in Exalted. That is, if two characters are created using the same resources, it's quite easy for one of them to be much more effective than the other. If one character is built on the fast track to godhood and the other is built to be able to do nifty things within their purview, God-guy is going to come out way ahead in the power curve for the same amount of effort (ie experience points).
A similar problem exists in Exalted as well. I think of it as the "Dexterity wins problem." Namely, if someone takes physical as their tertiary category and sticks all four points into Dexterity (leading to Str 1, Dex 5, Sta 1), the character will in almost all ways be more effective than someone who chose physical as primary who put no points in Dexterity (leading to Str 5, Dex 1, Sta 5). This problem is replicated in Scion then exacerbated through epic Attributes (or whatever exactly they're called).
The more interested in mechanical rigor, and the higher level of power your group takes it, the less Scion holds up under the strain.