I'm thinking more selfishly. Harvin and Boldin enter our division, Amendola is looking like an Eagle (or maybe a Raven?), Gibson is definitely gone...Bradford needs some serious help. Our three receivers after that are Chris Givens, Brian Quick and Austin Pettis.
The selfish side of me likes the Harvin trade. Not only does Harvin leave the NFC North, but I have him on my fantasy keeper league team and I think he'll put up more points with a halfway decent QB throwing to him.
The Vikings got pretty good compensation for Harvin, but WR was a position they were already weak at. I see some parallel to their Randy Moss trade years ago. Once again the deciding factor seems to personality issues rather than talent.