This is surprisingly effective and allows the story to be shaped (as Rikter's review points out) since many of the weakest parts of the original story were the dialogue of Jar Jar, the Gungans, and the Trade Federation.
I'm surprised to hear any objection to the Kyber Crystal, but I did not catch the "Splinter in the mind's eye" reference. Basically, for me, the backstory that Jar Jar had allowed it to be stolen accounted so much better for his actions that I was happy with it --
BUT (spoilers)
...then the final parade sequence involved Amidala giving the crystal back to the Gungan Boss and I had a giant grin on my face. Until then the entire final sequence had been irredeemably silly in my opinion (I even hated the John Williams music).
I've only watched with the ADigitalMan subtitles, so I guess I have another movie to try out by using MagnoliaFan's.
I felt, with the new dialogue, that Jar Jar was quite tolerable. I mean I liked him, I really liked him.
M