Hi Pete,
The lens has been great. Since posting this thread I have even got the 24-70 Tamron to pair with the 70-200. Is it as good as the Nikon…. no but it is very close. If I was a wedding photographer that needed to ensure that I got 'every' single image possible in a fast, high pressure situation, then I would have got the Nikon. Because the focusing is faster and does not falter at all. However for me, a happy amateur who also does the occasional family portrait work. The Tamron works perfectly. It is sharp, focuses well/quickly and is comfortable to use. And the big thing… it only cost me $1000 from a local supplier. I also do a lot of work with the local theatre company. This environment is tricky, it is fast, the lighting changes dramatically and I need to get a close crop portrait of individual actors as they are on the stage. The 70-200 is what I use all the time and it works great. The limitations come more from me then from the lens.

As MissionMan has stated the two tamron lenses have cost me $2000 total which is around what one of the nikon equivalents would have cost.

I did have a problem about 6 months in with the lens. It wouldn't focus at all at 200mm I took it back to "Georges" in Sydney where I got it from and they sent it to the Australian distributor (WA) and had it back to me within a few days working great again.

In summery….

If you are a pro that works in situations where you have one opportunity to get the perfect shot and therefore charge enough to not worry about cost buy the Nikon (however, due to the fact that you are asking advise I would suggest that this is not you )

If you are anybody else buy the Tamron you'll love it.

Hope this helps