I can't comment on the slim fit because, well, I haven't fit into anything slim since maybe the first couple years of college. They are very comfortable and I was very happy with the fit in my standard sizes. While I'm not a fashionista, it seems like the fabric is pretty darn good and I did pinpoint shirts and the patterns seem crisp and clear.
I had received a high-end enro(?) shirt from a top mens store in town and the fit on that was different from my other ones so I returned it and purchased 3 Jos A Bank shirts for the same price.
If you're buying online, search for a coupon code, I got even more off than their normal sales.