I playtested Shift a few months ago, then tried it out now on PC. its a lot better than old nFS but compared to GRID I'd prefer GRID over NFS. The collision physics in NFS are wonky and the handling is suspiciously arcadey even at pro mode levels.
All NFS Shift brings new to the table is satiating all the kids who love guitar hero and seeing points fly up all over the place for any action they do with ... "sweet" point multipliers and EPIC badges.
It's good for a quick diversion, and the car sounds are nice, but I wouldn't pay full price for it.