Bruce Lee lost faith in kung fu,do you think he was very knowledgeable in other styles besides Wing Chun?

Not at all. He made decisions and choices based on his personal experiences. He was a student of Wing Chun in Hong Kong, but when he came to America he realized that many of the tactics of Wing Chun didn't work for him against larger stronger opponents.

He began studying all different kinds of arts and using bits and pieces that worked well for him - Fencing and Boxing primarily, but he also has sketches of grappling and some strikes that look like Savate in the Tao of Jeet Kun Do (although he never intended to publishe those works, as they were more of a personal diary).

I don't think he made any judgements per se - he simply stated what worked for his goals and what didn't. He did feel as though a lot of the formalities were "window dressing" and not pertinent to the combat aspect of the martial arts, but I don't think he dismissed anything that he found effective. By that logic, you could say that he dismissed fencing, boxing, and other arts that he did not fully embrace. He wasn't a purist, clearly.

But if you watch his movements in movies or the few demonstrations that were filmed, you see that he uses WC type blocking and striking philosophy. Watch for the way that he keeps his hands protecting the centerline and almost always keeps his "wu sao" or protecting hand back. That's straight out of WC training! You even see him use chain punches, as well as a sort of skipping pak sao/gua choi (block/backfist) quite frequently on film.

Bottom line - he didn't lose faith in the totality of Kung Fu styles- he just felt that in its pure form it wasn't for him. Neither was fencing, boxing, savate, or karate.

LEE didn't lose faith in any fighting art whether it was kung fu or not .What he lost faith in was the way they were being taught.

As justin said he never stayed long 5 odd years in Wing Chun may get you a black belt but as many of us know thats only the tip of the iceberg that you have alot more work/learning in the art to do.

Wing Chun is a Shaolin Style and comes from animal styles, it incorporates many techniques from animal styles. It is popularly believed that Wing Chun was the result of 5 animal style grandmasters selecting the most efficent and effective techniques for their systems and developing them into a new style based on the bio mechanics of a human instead of an animal. This new art was supposed to be to train an army in a shorter time (5 years rather than the 10 years it took to master animal style) to take China back from the invading Manchurians. So there you go... If you want to learn one of those two then go for Wing Chun if you want to learn quicker or animal style if you've got a lot of time. Mind you it will take quite a while to learn to use wing chun effectively (at least 6 months to get some basic skill and knowledge working well and years to consider yourself a skilled practioner). Both styles are highly effective however I believe Wing Chun to be a little more so as you are constantly training in the manner that you fight, you do not have to modify anything for "real" situations.

He had a library of books on different styles, weights ect. He took the 'techniques' that work in real life situation and put them all together.
Although it would be nothing compared to what he would be able to achieve with the info available today.
He didn't like that most styles are hundreds or even thousands of years old and although we are much smarter, we teach the same as if it's the 'gospel truth.' Kind of like using the wright brothers airoplane desighn to create an airoplane today-it's old and outdated.
It is also 'organised despair.' Like planning a fight before it happens, you can train you 'tools' but you can not predict a fight. Which is part of the reason why he stopped teaching. (people were looking for techniques that would work-again that would make it another restricted style)

he lost faith in styles all together. and he did study those styles, just not alot. but he was a fast learner.

Bruce never finished his Wing Chung Kung Fu training. You see him using Wing Chung moves all the time, even Dim Mak which is Wing Chung as well as Bill Gee. All of Jeet Kun Do is flavored with Wing Chung. Bruce had for his height an incredible reach, he therefore adapted what worked well for him. I think had he lived longer to mellow out a little he would admit that no one style has all that is best for every individual; however you need to thoroughly become a master of one before you can judge it against all other arts.

He studied a lot of styles but did not go all the way through with them.

He practiced boxing.

Overall, I think he would've been regarded as an elite striker if he ever participated in MMA, he had really strong kicks, a respectable amount of boxing skill and a very athletic build.

I speculate he would've been the Mirko Filipovic of the fly weight division.

I dont really understand the question as bruce lee developed the concept of jeet kune do.He took the best techniques from all different styles of martial arts,he even studied fencing and observed the way they move when they are attacking etc

He used the techniques that he found usefull to his style of fighting,anybody who studies jeet kune do can take any technique they want from any martial art and apply in into thier training if they find it usefull to them.

He had a wing chun base but then studied philosophy and used philosophy in martial arts and the result of that was jeet kune do "the way of the intercepting fist"

"Be formless like water he said dont limit yourself to one particular style,flow like water be formless".

If you have a style that nobody has ever seen before they cant study you so they are unprepared for you when you fight,you can research them but they cant research you as you are all styles combined.

he studied things that worked if they didn't work for him he didn't continue with them, he looked for ways to become a better street fighter, he trained muay thai, savate, judo, jiu jitsu, wrestling, fencing, western boxing, and so on. he took techniques that worked and left out what didn't work.