I bought a tamron lens knowing that the reviews talked about the autofocus being "slow." The lens I got isn't "slow" pre se. it more confused. it will sometimes completely miss what focused is even on a few passes and on regular things, like blinds and slats, it sometimes thinks focused is no where near focused.

Should I ask for a replacement in case I got a bad one? Or just assume this is what the reviewers were talking about?

I'm not sure if I can get used to it or not. On one hand the price is much better than the competitor's (such that if I can't live with this lens, I do without), on the other hand, this was supposed to be the lens that lived on my camera most of the time, so the irritation might drive me batty.