I have had mine done and from what I can gather it drives a lot quieter and smoother than it did before.
I haven't noticed any difference in power - however I don't tow any trailers or anything like that and it seems to be the same off the road.
I did notice a change in the shift points though.
The positive for me is that it got rid of the 'binding feeling' i had in the tranny when I was taking off at lights (like it would clunk before I took off) - interestingly enough - when I complained of this sensation a few months before the dealer's mechanic said that it felt like suspension to him rater than transmission - go figure.