This lens is an excellent unit.
I have owned the new 77 mm and older 72 mm versions in Sony/minolta and Nikon mount and cannot find anything not to my liking.
I test a retest. At 2.8 it is sharp and at f4 even better.
On the Sony Alpha 100 with body anti shake it is outs tanding.
I have recommend it to many of my students and the only part negative comment comes from Canon mount users is that is a litte slower to focus that the Canon. It is not a light-weight unit ...Just buy it!
I have also owned the 28-80 mm 2.8 Tokina. It is a little longer and can focus closer but in my opinion not as quite as shrarp.