For the sake of accuracy, the Mylo does have a few minor points where it beats the 770.

1) The aforementioned keyboard - any way you look at it, it's going to come in handy.
2) It can be charged through the USB - more convenient.
3) 1 gig of built-in flash memory
4) Even if it only supports MPEG-4 videos, it's a good bet that the videos can be bigger and playback smoother than on the 770.

But of course, these points are minor compared to the huge drawbacks - small screen, only Sony's closed propietary apps, etc. (remarkably, BTW, the mylo has no regular audio jack. You need the special cable that comes with the device, which doubles as the audio-in. But if you forget or lose the special cable: no more headset or any sort of audio out! Unbelievable.)