First review: http://it.wyswig.com/2014/01/02/review-tamron-sp-150-600mm-f5-6-3-di-vc-usd-english-review/
I have a 400 5.6L. What makes me want to pre-order this lens is what he says about the advantage of the zoom. It's had to find and track a small bird with a long prime and being able to find your target and then zoom in for the shot makes sense to me or at least worth trying.
IQ and focus speed is not 500 F4L but neither is the weight and price.
Photowyzard: If the optics and IQ are as good as I expect, this will be the "next" lens in everyones kit. I can hardly wait to see what type of image this Tamron delivers for $1200.
I guess the question is: does 200 mm and VC trump the Canon 400 5.6L. The extra 700 grams enters the equation too at some point. At $1069 the Tamron is $150 less than the Canon 400 prime (AR). It's going to be interesting.
$1069. This thing is going to get wriiten up in no time. The low price could mean that it can't stand up against a Canon 400L. Maybe it will put a little pressure on Canon to stabilize the 400 5.6L.
What it comes down to for me is the 1.5 lbs more that the 150-600 weighs over my 400 5.6L. How much difference in IQ and reach and how well the VC works for hand holding. If Tamron is less than $2K, I'm willing to buy one and find out. Why Canon hasn't stabilized the 400 5.6L is beyond me.