The 35 diesel will be somewhat slower off the line than the 35 gasoline, but the torque lets it accelerate much better than the gasoline when you are at highway speeds. So it's better for passing and emergency maneuvers.
The additional torque also makes it move with more authority up big hills (which is very useful out here in San Francisco where I live.)
On the economic front, the 35 diesel will definitely save money vs the 50 gasoline, both on the initial purchase price and on the fuel costs, but it's true that it's at best a wash vs the 35 gas over the three or four years you might have the car. (But, note to Coconut780, diesel engines usually need less maintenance and have a longer life than gasoline ones.)
One other non-economic reason for going with the diesel: it has lower emissions than the gasoline, which is a good thing if you care about global warming
