i havent used any of them but as per reviews satio has 16M colors whereas X10 has only 65k colors..
Satio 12 Mp + powerful XENON flash ... Xperia 8MP camera with led flash only, which is not powerful at all..
Satio Ram: 256 MB ... Xperia Ram 384 MB
Satio internal memory is quiet low, its 128 MB only .. whereas xperia is having 1 GB internal memory...
Satio processing speed is only 600 MHZ whereas xpeia has 1 GHZ
Battery is almost same for both but to me, xperia will consume more as there is hell lot of things u do with android phones such as awesome apps and games which satio doesn't offer..
now its up to u which one would be suitable for u