Overall, I like it.
I don't think the desaturated look fits with the character and the game; almost all the in-game styling in FFX is very colorful and saturated. Especially the red and blue in the clothing, you're losing too much color there when you overlay the effects. Some additional greens in the background foliage would help too - even if the green doesn't already exist back there, it wouldn't hurt to add it. Optionally, you could also make the overdrive effects yellow; in the game, the "readying" is yellow and blue but the actual tornado is white.
I usually grumble about cutting off limbs (his leading foot) but I don't know if it really detracts here. I night have gone with a slightly looser composition.
The loss of detail in the leading arm kinda bugs me.