The lens has a sonic wave autofocus drive (SSM) which is moderately, but not blazingly, fast. But it's quick enough to track birds in flight, is accurate, and very quiet. For someone used to older minolta screw drives, and some of the Sony rebadged lenses, it's a bit disconcerting at first as you expect to hear it as well as see it snapping into focus.
It's heavy, one of the heaviest zooms in its class, which is surprising since it doesn't have any IS/VR servos, relying on the Sony in-camera 'steady-shot' image stabilisation.
The colour of the lens, silver, has been a topic of much discussion on Alpha mount forums, with most people not liking it very much. Sony has apparently attempted to differentiate itself from Nikon (black) and Canon (cream). Unfortunately there was a period when Konika joined Minolta in producing very cheap plastic cameras and lenses. Although there were a few surprisingly good examples, many of these lenses were dreadful, and they were silver. Meanwhile, Minolta continued producing its superb G quality lenses which were white, and Sony's rebadges of these are still, wait for it, white!
The camera buying public are fickle, and this choice of colour may be a bit of a marketing cock-up by Sony, but it still appears to be one of Camera World's best sellers. Part of the reason for this is obvious: once you've got a Sony DSLR and you look around for a wildlife lens for it you find Sony's real achilles heel, and Gary's (Gruditch) past comments about the paucity of long lenses in Alpha mount are not without substance. Unless you go independent, there hasn't been a lot about at longer focal lengths. But the other reason is that this lens is astonishingly good at all apertures and focal lengths, and with recent price rises, by Sigma in particular, the Sony zoom is a no-brainer purchase.
You can stick a Sony 1.4x teleconverter on it to get 560mm focal length but it will switch to manual focus. However, a Sigma 1.4x EX teleconverter will also fit, and it'll autofocus, although it'll hunt in poor light. Preliminary results with my Sigma TC have been good with good centre resolution, although slipping a bit at the edges when at full aperture.
The zoom will focus down to less than 1.5m giving about 1:3 semi-macro ability at 400mm focal length, or around 1:2 with the TC attached.
Here's a couple of extreme examples showing the lens' versatility. Both were shot with the A700 camera without teleconverter or any other attachments. I used a monopod for both.
I only use a tripod for macro work, or if I'm planning to do some slow exposures, otherwise I rarely use a tripod. 