[Review for the Nikon fit lens]
Cheap - if you aren't looking for crystal clarity and will use it only in circumstances where camera shake won't be a big deal (i.e. not at full focal length, using a tripod or in full sunlight), you can get surprisingly good images. It'll never compete quality-wise with a £2000 pro lens, but at this price it doesn't have to.
Near-macro performance (1:2 isn't full macro) unless you're wanting to get up close and personal with individual ants, it makes for a passable macro lens. Remember to use that tripod, though.
Overall value - in the world of SLR photography, you rarely get much for less that £150, especially when it's a long zoom with macro functionality.
Construction quality is ok, and while it can look impressive fully extended, to handle it can start to appear flimsy, and feels more blue peter than blue ribbon. I have doubts over its long term survival. At this price though, it's hard to complain.
Image Quality is good in the 70-150mm range with no real problems, but as you approach 300mm you start to see blurring creep in from the sides, and chromatic abberation becomes an issue in high contrast areas (e.g. tree branches against the sky). Worse than my other lenses, but still not so bad as to make your photos unusable.
In summary it's an average to good quality lens, and for people who want something to cover those full zoom scenarios they might need on the odd occasion without breaking the bank, it would be hard to do better. If I needed a 300mm lens on a daily basis though, I'd definately look at a higher end model (and accompanying higher end price tag).