I got this lense on friday from B&H. It was a tough one to buy but oh was it worth it. I kept checking B&H every now and then to see when it would say "In stock." I always trust Fedex so here's a bit of Irony.
My manager called me and said I could come in 1 hour late because Fedex failed to deliver a new shipment. If it wasn't for this I wouldn't have been home to catch the lense when it became "In stock." I refresh the page and it says "In stock" I order it faster than lightning and 5 minutes later it was "Out of stock." This lense sold out in 10 minutes......
To thank Fedex I made sure to use them as the shipper. 
Enough of that here's my little review.
Build:
Like a tank. It has heft to it and feels super solid. The grip for the focus and zoom are awesome and rubber. Love it. The lens hood is awesome as well.
Feel:
The focus is super smooth. The zoom is smooth but doesn't turn easy enough to creep if the lens is hanging. They provided a lock so it doesn't creep...but it doesn't creep without it. This lense makes the XT feel like a whole different camera.
Function:
Focuses pretty damn fast and I see no problem with it hunting in low light. Yesterday I was shooting at 1600 ISO without a flash indoors with a shutter speed of 60 and I got very good non blurry pictures. I could not do this with the kit lense at all. The first thing I did when I got it was take the focus test chart I printed out from that one guy's site and tested it. It was dead on.
Optics:
Blows away the kit lense. My copy is sharp throughout all zoom ranges and aperatures. I think I got lucky....
Now here are some sample pictures. I made some at 2.8 to show the insanely shallow DOF. I love the "bokeh" on this lense.
First lets see how it looks on the XT (sorry for the bad quality pictures of it...Only had one tripod). The front element on this thing is huge. Looks really nice.


