Wow, that shift to f/1.4 from f/1.7 is just hard to believe. If I had not witnessed it, I would not believe the difference in exposure level. As Ken writes, is this lens incredibly sharp, and fast in its auto focus. I had been using an F/1.7 for years with my Alpha 100, and was thrilled about it, not believing it could become much better… but I was wrong this lens is magicalJ. Extremely low light work and indoor flashless photography. The usual superb Minolta colours and it is a particularly excellent for high contrast black and white photography. It has a very nice bokeh. My version of the lens is sharp in the middle at F/1.4 then, but it really shines in the area of F/2-F/11
On a budget
The lens is selling at some 250$, so if money were a concern, then you might want go with the F/1.7 version. On the other hand if you got a full frame, then this lens is magic… it is twice as expensive as the F/1.7 for the reason that it is at least twice as good.
Insight that is more technical, can be found at Ken Rockwell.