Sure, for your finger it's only a small distance. But for your mind, it "feels" like a long distance.

I tried several transition effects, including Jolla's one, for a mobile application. Half-transparency was quickly disqualified as it neither allows to comfortably "peek", nor to make it obvious what's happening. Furthermore, there is no real-life association which makes the move unnatural.

I personnally did not install more that 3 or 4 apps and also (or especially) in that case, the application grid does not fill right. WP has an interesting (and radical) approach because it combines the tiles with the launchers and thus removes one dimension. But there are probably better ideas to explore, this is grid is absolutly not unlike...

Anyway, there are some really nice ideas and the concept is much stronger than any widget-like approach with 5 to 10 home screens