As a Sens fan I could not be happier with this.
Cowen is by far the worst defenceman to play in the NHL in the last little while. It's not a "settling in" thing, he's just a dunce and can't think fast enough. Always out of position, can't get his head up to make a pass, crazy slow reaction time... just an utterly awful hockey player. I am 99% certain that he is unfixable, because he was never actually good to begin with. Greening also really, really sucks. Michalek has been ravaged by injuries and is now pretty redundant for the Senators, as they've got Hoffman, Ryan, MacArthur and Stone to play wing on their top 2 lines.
Plus look at what these guys are owed next year:
$4.5 million, Cowen
$4 million, Michalek
$3.2 million, Greening
That's $11.7 million next year, plus what they're saving for the rest of this year. The monetary benefits kick in for the Leafs starting in 2017-18, but they've given up $4.2 million in cap space next year.
Lindberg is supposed to be a 2nd/3rd line player, but he's going to be touted as a blue chipper because he's on the Leafs now. He wasn't in the Senators top 10 prospects.
Phaneuf seems like kind of a dick and is definitely not a franchise defenceman, but playing for the Leafs is awful for anyone's career. I think this is a case of a fanbase scapegoating one of their best players because the team as a whole isn't very good. He'll either play with Karlsson and look really good (see Kuba, Filip 2011-12 season), or good against weaker opponents on the 2nd pairing.
I guess fans of other teams will look at this deal without knowing all this and think Toronto did a good job here, but the Sens 1) got rid of their 3 worst contracts, 2) got a pretty good player to shore up the weakest part of their team, and 3) gave up none of their top 10 prospects.