Not a ton of change but there area few things. The tongue changed from the thing piece of cloth to a nice padded tongue that feels better and makes the lacing feel less noticeable. They a but more cushiony to me too. Every step feels soft but not like Hoka soft. The back behind the heel changed a bit too. I've noticed that the area below the support frame seems kinda saggy on all that I've seen. I can't feel it though, just a visual thing. My Freedoms ISOs got holes on the outside of the toe box long before the rest of the shoe was really wearing out but the ISO 2's have more padding in that area which seems to prevent that. I like the ISO 2's more than the originals. Just generally more durable and feel more like a shoe that can handle a lot of miles.