I'm not too sure how the newer Mali GPU in the Exynos 4412 (which is just an overclocked Mali-400, not their newer Mali-600 series) will perform. However, you can use this as a reference:
This compares the Adreno 225 (the GPU the S4 will launch with, eventually upgraded to the 320 later in the year) which is essentially an overclocked Adreno 220, to the Mali 400 (GPU in the S2). As you can see, the Adreno 225 is on top in virtually everything, although I'd imagine the gap tightens significantly with the overclocked Mali-400.
All in all, I'd imagine both GPUs to be roughly similar, while the S4 krait should dominate in single/dual threaded apps and power efficiency.