I have the Tamron 70-300 LD DI (don't get the other version of this lens -- the non DI -- it is awful).
I have taken many pictures with it, it is sharp, light and inexpensive. It is quite "plastic" and I wouldn't want to bang it around, it is slow, and it isn't the fastest focusing lens out there either. The 1:2 macro actually works pretty well, although obviously it is not a true macro.
I have taken over 10K pictures with the Tamron 70-300 and it looks and acts absolutely brand new.
Later I will put up a few sample pictures if you want to see them (I have posted samples before, but they have been seen here several times, it is time to put up something fresh).