I played with a guy who bought like 5 Ions and he loves them. They have a really nice feel to them but I am afraid that are not overstable enough for my liking. I typically use my Zone as my main putter and love the low profile, super overstable, most predictable putter I have ever thrown nature of it.
Well, you do throw Zones. Wait for the medium Ions to come out, they'll be more to your liking I bet.