The graphics performance makes a big leap every year. And Tim Sweeney was on board with UE3 last time (at least on iOS and Windows RT).
A perf. leap is only half the equation, because perf. still needs to be high enough to be playable 🙂
Kepler.M inside Tegra K1 is arguably the first ultra-mobile GPU that has comparable (or better) overall GPU + CPU performance compared to PS3 and Xbox 360