I think that he makes a lot of very good points. It's great to hear this right from the horse's mouth. Very refreshing.
Personally I hate flash, what he says about Mac's crashing because of it couldn't be more to the point (I experienced it a few times). The sooner it goes away the better. This morning I brought up the nhl.com web page on my iPad to find everything working perfectly, even the videos, with no flash whatsoever.
And please, I heard this argument about open/closed in other forums too. Read the letter again, Jobs readily admits that Apple has many closed and proprietary platforms. When he refers to openness he's talking about web standards.
Imagine if Apple would have waited for Adobe to deliver a good mobile flash application, we still wouldn't have the iPhone, iTouch and iPad...
Don't get me wrong, before you think I'm some mindless Apple kool-aid drinker, I fully realize that Apple is first and foremost a for-profit organization and that to a certain extent they are trying to protect their business by not allowing flash. That is certainly part of the equation, but obviously not the only reason, as this letter just proves.
Mods, can we have a poll on this one?