With anything new, you'll have a group that claims that any new technology is unreliable, not as good as the old proven standby, etc, etc, and you'll have a group that embraces the technology. The only reason you hear mixed reviews on the Auto Tune is the few problems that people have aren't fixed with a simple turn of a couple screws anymore, and the first group that I mentioned, well they find that absolutely appalling. How dare they release anything without years of field testing, blah, blah, blah?!?
Husqvarna surely sunk a large sum of funds into the development of the AutoTune system, are there some hiccups occasionally, sure, but to continue the development until the system is 100% flawless would have cost exponentially more. How many test saws would you have to run the have a six sigma confidence level that you won't have any issues in the field?
Mixed reviews, either love it or hate it. It either works great or damn this inferior product because I can't fix it. Just pick a side.
I have a 555, obviously with AT, and I love it. But, I'm biased, I like new tech, I like being an early adopter.