by "creator of REX" i suppose you mean "creator of REZ?" "q entertainment" is the name of miziguchi's company, right? looks like his new game is on psp rather than ds after all. nice. a spiritual successor to rez with n64 graphics and chip music would've made me cry.
i think the games we've seen look comparable to first gen ps2 games. gt4 mobile will be the game to judge the hardware by -- if polyphony port the game "without compromise" as they intend, then that'll be considerably more impressive than any of the early ps2 software.