Short Hands-on Article From London Vita Event

http://www.nowgamer.com/news/1142212/gravity_rush_is_ps_vitas_most_beautiful_game.html

Very positive write up, reaffirms the open nature of the game as well.

Gamescom Hands-on Previews

A few hands-on impressions:
Gamesradar (the longest preview of these four)
Dualshockers
Push Square (suggests that the game may be a PSN release, not a full retail one, but not confirmed)
Machinima

Some details on missions, combat and characters

Some older articles from Siliconera:
Mission Structure
Combat
Character