Originally Posted by
GrumpyDiver
My understanding is that the older model has a slightly faster maximum aperture f/5.6 versus f/6.3 (i.e. 1/3 stop). Optical performance is similar. You've already noted the weight; the newer lens weighs a lot less (around 10 oz, 300g) than the older lens.
As mentioned before, for a number of reasons, it is going to be a marginal wildlife lens, but if the lighting is good and you are close enough, you should be able to pull off some decent shots.
It is also not a macro lens; closest focus distance is around 0.5m. So closeups, perhaps, but definitely not true 1:1 macro shots.
Portraits, yes, you should be able to do decent portraits with this lens, but with its 7-blade design, you are not going to get that great, creamy bokeh that the higher end lenses are going to give you.
As with any "all purpose" lens, the lens designers have had to consider too many trade offs to be able to produce a lens with outstanding performance characteristics. It is a good lens, not a great lens.