It's certainly a great GPU, but benchmarks have shown that core-for-core, the A17 Pro GPU (on which the M3 is based) doesn't perform better than the A16 GPU for rasterization.
Il will probably prove faster in tasks using mesh shaders though.
EDIT: first GFXBench results confirm it. The gains are marginal compared to M2.
https://gfxbench.com/device.jsp?benchmark=gfx50&os=OS X&api=metal&cpu-arch=ARM&hwtype=GPU&hwname=Apple M3&did=118295482&D=Apple M3
For compute, it's the same story. Geekbench reports scores close to 30000, while the M2 scores at about 28000.
We're talking about <10% gains.
M2 brought much greater improvements in these aspects.