Anyone in particular you are looking at? They're excellent lenses, among the ones that seem to be well suited to life on the NEX are the 40/1.8 (Tokina made), 50/1.4, 135/3.2 and my favorite the 24/2.8.
The 57/1.4 uses (as I recall) the same optical formula as the much loved 57/1.2 (thought by some to be the best 1.2 from any maker). Unfortunately I don't have any experience with either lens. There is an excellent resource for Konica lenses HERE. I refer to it often. I have always like Konica lenses. I currently have a 24/2.8, 35/2.8 and 200/3.5 that I like quite a bit. The 24/2.8 is a large lens (although not as heavy as my Rokkor 24) with excellent sharpness and terrific OOF backgrounds. It's a bit pricey (mine was $175) but IMHO it's a bit sharper than my Rokkor 24 which is reputed to be a design that Leica used as their 24/2.8 R lens.
I thought the Konica 40 was pretty sharp stopped down but wide open it's pretty glowy and soft. The bokeh IMHO was pretty busy. I have had a few of them and I always end up selling them. Some copies have been better than others. I'd love a 28/1.8. I just picked up a 35/2.8 and it's pretty decent. I think it's an underrated lens.