I'm biased, but anyway it really is a damn fine putter, especially as a driving putter. It is lower profile and feels chunky in the hand (easier to powergrip for me), flies pretty fast and still has a very decent glide (especially if you give it some spin), has plenty of HSS (even the baseline can handle itself in the wind, the premiums really shine in headwind) with a reliable but not that drastic fade (the premiums fade a bit more, but not much). Works beautifully on flex shots from what I've tried. Basically when I deem the wind to be too harsh for the ION or want more fade at the end of the flight, I reach for the JOKERi.
The baseline is tacky as hell (loving it in the winter), and while flexy it isn't mushy, won't interfere with push putting. I've also thrown one of mine against a wall a couple of times to test it out, and while it did dent (what baseline wouldn't?) it didn't affect the flight at all, in the air it's indistinguishable from a brand new one. The Premiums are probably the clearest champ-type plastic you've ever seen, and dye really well. Stiffness is on the gummy side.
Basically they're a wonderful complement to the ION, especially if you like a more low-profile feel.
EDIT: Oh yeah, apart from being terrific driving putters they're also good for approaches and putting too. Too LSS for spin putting for my tastes, but that's why I have my FR IONs.
