Tough call. Very tough, actually.
You'd essentially be replacing Varitek, Polanco and Green with I.Rodriguez, Soriano and T.Martinez or Blalock (assuming you play McLemore at of), depending on how well Blalock does, which sounds like a significant upgrade in both speed and power.
The downside, however, is that Pudge comes with a substantial risk. He came to camp overweight and out of shape, bad signs for a catcher. Soriano has some question marks, too: everyone expects that his plate discipline will improve, but that's not a given.
Varitek is no sure thing either, of course. It looks like he could take a while to return to his old form. Of the players in this trade, only Green comes without serious question marks, which is reason enough to be a bit skeptical.
How soon do you have to decide this? If I were you, I'd first see if I could make a different deal instead of this one, perhaps by offering Blalock for upgrades at c and/or 2b. Blalock's stock is high, and you're already set at 3b - you might be able to plug your holes without dealing Green.
If no other options are available, however, I'd probably accept this deal, not because you're getting significantly better players, but because of the configuration of your team. But hopefully you can upgrade at 2b (and maybe at c) in some other way.
Let us know what you decide!