The French version of OPSM2 includes a 4 page preview of VCS with some new Info. Its in French (obivisly) but acording to vcspsp.com it says:
Vice City Stories takes up a little more memory than the original Vice City on the disc.
In the version that they played the streets seemed a little empty, however Rockstar Games assured the editors that in the final version the streets would be twice as full with pedestrians and vehicles.
Rockstar are also promising a big surprise concerning the WiFi features of Vice City Stories, though that's all they're saying for the moment.
It's also said that there's going to be a lot of humour in the game concerning the pair of Vances.
Scans:
Scan 1
Scan 2
Scan 3
Scan 4