In a way I agree with NEELY's first comment -- hard to really tell until you see it on a jersey. And I somewhat agree with SD's initial reaction -- i.e. not really a fan. That said, I think I'm a bit leery of round logos if they are too small on the chest -- makes them look like a target. Some of my favorites are round or primarily round (Boston, Detroit), but as much as I liked the Sens' 2-D logo the reason I haven't got a jersey with it is the logo is too small.
Oh, and as much as I may agree that the current 3D logo is better than the previous one, I still much prefer the 2D spartan to the current design. I like my logos like logos and not pictures; don' need shadows to tell me it's meant to be 3D because logos don't need to be 3D. It should be a design, not a picture.
Of course that's all just an opinion.
Edit: Just took another look at Detroit and Boston's logo -- Detroit really isn't circular at all, is it? I think Boston's is may be only circular logo I really like.