Limited budget fast zoom?

it is indeed, best from F/4 and up. But the problem with the delamitation is real, like Catallaxy said. The lens must be well checked when bought used. The OP could look closely inside, under a light and check if the internal elements appear pale, hazy. it's the cement used to glue the elements that is deteriorating. The fix may cost around 200 bucks. Ive seen it and it's bad.
but if the lens is good then it's a keeper, hands down.