Some Notes on Judo as Self Defense From an Admittedly Biased Proponent:
OK, all of the above is true, to a certain extent. And I don't want to start some sort of holy war between judokas and karate guys, or vi users and emiacs, or whatever, but I have to note this:
Judo is an excellent form of self defense.
Why?

Well, not just because of it's throws, joint locks, chokes, or rarely practiced striking techniques. Not for its philosophy of mutual benefit, or maximum efficiency. Instead, because judo is one of the few martial arts that requires participants to practice its techniques at full speed and full strength. The ability to practice potentially deadly techniques at full speed, against a trained and unwilling human being, gives judokas an amazing head start in real world self defense.

Shiai, or tournament competition, is highly encouraged by most Judo senseis--and was highly encouraged by Jigoro Kano himself, for that matter. Sickened by jiu-jitsu "Death matches", part of his motivation to create Judo revolved around his inability to fully practice the more dangerous techniques. He removed many, adapted others, and created "the way of flexibility", or gentleness as it is more commonly translated.

Now, I acknowledge there are a myriad of ways to defend oneself, starting with mouth (for fast talking) and feet (for running!). Also, Judo has some real weaknesses--number one the lack of emphaisis on striking techniques. But, the physical strength gained through judo training, added to the techniques taught and practiced, make judo a formidable method for protecting your person.

And if you still have your doubts about Judo's effectiveness, show up at your local judo dojo and pick a fight. You'll find at least one guy that will help you see the light.