The 100-300 apo D is optically identical to the 100-300 apo which I have used for around 10 years. It's principal attributes are its compact, handy size and decent build quality. It balances beautifully on the Maxxum/Dynax 7. Optically, like most zooms in this class, it is a touch soft wide open at 300mm. However this improves significantly by f6.7, and by f8 its performance is very good. At 100 and 200mm it is fine at essentially all apertures.
Recently I acquired the Minolta 300mm f4 apo G. There is a marked difference in contrast and sharpness between this lens and the 100-300 apo, particularly wide open. However in fairness this applies to almost almost all telezooms in this range when compared to much more costly prime lenses of the same focal length. AF on the Dynax 7 is also significantly faster with the prime, although it's pretty decent with the 100-300 apo anyway.
In summary, I have found the 100-300 apo to be a very versatile, useful lens. It makes a great pair with the Minolta 24-105D or 24-85. Stay away from f5.6 at 300mm and I think you will be very pleased with the results. ( For sport work I used to simply select aperture priority at f6.7 and shoot away with ISO 400 film).
POP reviewed the 100-300 apo years ago, and this review can be purchased from them. In summary they found it to have above average performance, with unusually low field curvature for this class. That means that sharpness holds up well to the edges of the frame - normally a weakness for lenses in this class. www.photodo.com also has a review, and the lens was rated better than most consunmer telzooms in this class.You could also check out Photozone, which has user ratings, and www.photographyreview.com where you will find my review amongst others.