Previously rather disappointed - Update 24.07.2012

Update 24/07/2012: "New Body, new experience"
I could now test the lens on my Canon 7D and have the vote now increased to 4 stars.
The problems shown on the 450D dive here no longer. Focussing is pleasantly quickly and accurately, the images are sharp and may now liked!
For, now again lowered price, now a strong buy recommendation!

I prefer certainly my combination 7D and the 70-200 f4 L, but come as needed now also like the Tamron back!

Update 29/02/2012: Further preliminary review! Rest see from ### Update 29.02.2012 in the text below ###
Situation: I've bought said lens for my Canon EOS 450D in order to better set series animal shots while moving in scene.
My previous kit lens, the Canon EF-S 55-250mm 4.0-5.6 IS II has very nice, crisp images delivered, provided that the autofocus behind came from.
This was ultimately the purchase decision for the Tamron, which described very good price / performance ratio, the excellent image stabilization, especially the ultrasonic motor ring.
To feel, the lens feels very valuable to the plastic looks good (for plastic) and you really have to keep feeling a high-quality lens in his hands.
The weight is clearly noticeable as for example the Canon EF-S 50-250, but not annoying.
On the other hand getting used to was the zooming, because, contrary to the usual direction of rotation of the Canon lenses own runs exactly.
The first recordings then were disappointing for me, often hit the autofocus is not what was envisaged, but a sample on a scale plate resulted in a 100% accurate focus center.
The dog in this case were rarely really sharp in action shots.
I have next week an appointment with a photographer friend, let's see if the "fault" lies with me or in the technique or what ever, then I will, if appropriate, modify or complete this review, until then receives this objective by me only 2 stars, because it is good for stationary objects, with moving animals but for me is currently unpredictable.

### Update 29/02/2012 ###
After yesterday's meeting, in which, unfortunately, due to poor weather conditions no action exterior shots were done, I still found new approaches to alleviate my problem possibly.
The next session in better weather then show it.
What was clearly seen is that he can keep up the USM Autofocus Tamron in no case with a Canon 70-200 4L.

I stay with a current personal rating of 3 stars.