The ACX3 is a much better fit & is lighter and slimmer than the cover I had on earlier - a hard back cover I got off ebay.
Because it is an all in one solution, the double size of the hard cover+ACX2 is avoided. It is much easier to hold or keep in a trouser front pocket.
I had an issue with my previous cover that I could not charge it using the DK30 dock. The same issue occurred with the SPA-ACX3 cover. But I realized that I could just put some bubble wrap (a small piece cut out and rolled) into the DK30 that pushed up the magnetic connector. That way it charges with the cover on. Brilliant.
I am quite happy. I just wish Sony made these available more easily and at the price indicated at launch (about $30 or so).