The one thing that worries me about the trade, now that Harvin is out for most of the year, is that Cordarelle Patterson was there with the 1st round pick we gave up (and went with that pick to the Vikings). I don't have any illusions that Patterson is as NFL-ready right now as Harvin (were Harvin healthy), but I think he could have filled that play-making role this season, and might even have more upside than Harvin for the future (and either way would have been significantly cheaper, and likely less fragile).
As far as what we gave up, I think it was a reasonable deal for a player of Harvin's ability... it just sucks that he won't be seen most of the season (if at all).