If this deal ends up like many sources have it then there would be a somewhat lateral movement for the Phillies this year, but an actual improvement for the future.
As of now:
Blue Jays get:
The Phillies would cumulatively lose only their top catching prospects as they would receive a top pitching prospect and a top outfield prospect. Michael Taylor is a little better than Tyson Gillies and Kyle Drabek is better than Phillippe Aumont, but, they are all prospects, which have proven nothing yet.
If this trade is made official the Phillies rotation will consist of Roy Halladay, Cole Hamels, Joe Blanton, J.A. Happ plus a fifth starter. This is great for the organization because the top 4 will be in Philadelphia for a few more years with the only change at the fifth starter position.
Losing only a catching prospect (who is blocked for the next 4 or 5 years anyway) is a good deal for the Phillies. I will miss Cliff Lee as much as anyone, but this needed to be done, and once again, Ruben Amaro Jr. did a great job in securing the present and the future for the Philadelphis Phillies.