I'll have to go on the yes / no thing here and break it down.
Here's a relavent quote:
"There were good basketball players, and then there was Michael Jordan. And there were good martial artists, and then there was Bruce Lee."
- Sifu Dan Inosanto (yesterday, and probably a few times before)
I think it's a good analogy. Was Jordan or Lee invincible and unstoppable? Of course not, but they were probably the best in their time (at least in this country).
That said, I'd also like to add a couple of other points.
Sijo Bruce Lee was definately gifted, but he also trained pretty damn hard. Sifu Dan mentioned that he would do focus glove training with him 2 hours a day. I understand he trained something like 6 hours a day. He wasn't just good out of luck, he worked at it, much harder than most.
Now breaking things down a bit. I think he was an amazing fighter, with superior speed, reflexes, strength, training and technique. I think he did an amazing job developing Jeet Kune Do (fighting structure and philosophy) - and I wouldn't call it plagarism, as he was synthesizing various ideas. That's called research, otherwise nobody would get their Ph. Ds.
Most people don't mention this, but I don't think he could have been a better teacher. What he did opened people's eyes, which was great. Unfortunately, I think as he would progress, he'd forget the importance of certain aspects of his earlier training. For example, when he threw out Chi Sao - he didn't find it important / relavent anymore, probably because he already had that sensitivity as second nature. But a begining student, especially one without any martial arts expereince before, would then have a difficult time learning trapping energy without learning that base.
I feel he got frustrated by large classes. That's probably why he closed down the Jun Fan Institute, opting for one on one instruction. That's fine if you can afford one on one classes, but I can't.
His acting, I feel was adequate for the time - I think he just charismad his way through some of those films. I don't think his directing was particularly good, at least compared to Hollywood standards - I haven't seen a lot of Hong Kong movies of the time, so I can't really compare apples to apples. The fight scenes in Return of the Dragon were great, it's just the rest of the directing could have been better.