Without any doubt, Phenom II X6 1090T is the best thing AMD can offer based on their current K10.5 architecture. It is my belief that it will be very hard to squeeze even more out of it before the new Bulldozer architecture comes out. Six phsical cores running cool at reasonable power consumption and on top of that clocked almost sky high. Backward compatibility is a major plus here, enabling AM2+/AM3 users with older chipsets to do a simple and straightforward processor upgrade. Performance wise, Phenom II X6 1090T meets the expectations, matching and exceeding performance of AMD's fastest quad-core Phenom II X4 965 and its competitors Intel Core i7 920 and 860.
If you do a lot of video editing or 3D rendering you will be very pleased as these are by far the strongest points of this processor, thanks to good multithreading optimizations. In single threaded tasks 1090T still manages to outperform AMD's other offerings, but it rarely matches the performance of Intel's Core i7.
Overclockers should also have a ton of fun with these processors, as they offer solid overclocking possibilities, if you have decent cooling and a quality power supply with abundance of power.

The only bad thing with Phenom II X4 1090T at the moment is its price tag. The MSRP stands at $295 but prices in stores currently start at $310, possibly due to short supply, making it harder for 1090T to compete with the slightly cheaper Core i7 860. In terms of theoretical raw performance, Phenom II X6 1090T can match or even outperform (video/3D applications) Core i7 860, but currently Intel has the upper hand due to the lower price tag, lower power consumption and a bit better overall performance.
But to say Phenom II X6 1090T is a bad product would be the same as saying Core i7 860 is a bad product. Considering Intel Core i7 860 is probably the best value processor from Intel, 1090T is holding its ground maybe even better than expected. AMD gave its best shot to threaten Intel in upper market segments and managed to throw one hell of a punch - again. Now they just have to work on getting those cores out there in decent numbers, to beat Intel in the current price war and hang tight until Bulldozer is ready.