My disc is ever so slightly concave on top. I'm not sure if that's standard or if I have a disc that is a little off from the norm. Whatever the case, it doesn't appear to be causing an issue. I haven't done a lot of true putting with it yet, but it feels good and releases from the hand without trouble for me, and isn't too different from the putters I've been used to for the past 2-3 years, so doesn't take too long to get a feel for it. I actually prefer this as an approach disc with longer throws: It's easier to throw for distance than my traditional putters -- I think because of its slightly narrower profile and being beadless. I get surprisingly long throws with the Nuno, yet still with the kind of straight flight and flat, controlled landing expected with putters. I think the feel, mild stability, low speed and good glide should make this a disc beginners can be comfortable and successful with, and even as they grow into more powerful throws, it should still remain useful.