I think there is a lot of animosity on what the Seahawks gave up and received in both trades. However, if you hypothetically clump them together as if it were a three team trade... (hell, possibly on trades related trades together)... and you get something very practical.
Minnesota receives 1st (2013), 7th (I think Buffalo's we got for Tarvaris Jackson who was signed as a free agent in 2011), and our 3rd Round pick in 2014.
So to Harvin we traded our 1st round pick and presumably a 4th round value in 2014 plus in a matter of speaking Tarvaris Jackson back to Minnesota.
Then we traded to Oakland, Matt Flynn who was SIGNED as a free agent in 2012, a QB with only 2 starts in what 5 years, a QB with about 16 starts his whole career... for a pair of rumored 5th round picks in both 2014, and 2015... not to mention about 10 million save in cap space in 2013 and 2014. (Different FO at the time but we also have to thank Oakland for taking Aaron Curry off our hands )
And if you put it all together, now, we pretty much traded a 2013 1st rounder, somewhat Matt Flynn*, and Tarvaris Jackson for Percy Harvin who is a 24 year old 4 yr vet now blossoming into an elite tier WR, is one of the best YAC threats in the league that give the Seahawks the elusive, separation inducing WR that Wilson's Offense lacks, and is one of the only players that can be considered an upgrade over Leon Washington in the return game.
*what we traded Flynn for might not equate into a 3rd rounder but if we resign players with that created cap space then imo it could be worth more in perspective of keeping quality players over the unknown.