http://howstuffworks.com has a lot of info on diesel and diesel engines.
That's not quite right about diesel not burning at lower pressures, tho. You're probably thinking of how diesel engines use much higher pressure compressed air in the combustion process than gasoline engines. Which makes them much more efficient reactors, chemically speaking.
The only cons to diesel I've heard are that the engines cost more to make and the emissions tend to be higher in NOCs. Supposedly though, there are cheap catalysts you can add to the biodiesel to greatly reduce the NOCs (to even lower values than petroleum fuels, if you believe the bio suppliers' websites).
One of my coworkers just got VW with a diesel engine, and this has been a topic of some discussion at the studio.
It seems to me, that if we (the US) REALLY wanted to do something about our energy concerns, we could make gasoline engines a niche market by 2025. But then, I don't know how much agriculture it would really take to sustain our fuel requirements, that is if it's even feasible.