I think I'll stick to my old plan for the next year until they force me to swap.
Biggest changes are that the unlimited data goes away, as well as the ability to select between 3G/4G. Based on my current usage and the new price structure, I don't think that will matter too much to me. They're basically capping the $25/mo rate to 1 GB, and I typically do not go over 1 GB/mo. They're going to a more TING-like "buckets" pricing structure, complicated a bit with "refund" language (why not just say that your rate is $15/GB? I guess "refund" sounds better!). Ting's pricing above 2 GB is basically $15/GB also, so this looks directly aimed at them.
Also, I note, buried in the text of the 2.0 document, that roaming data will now be charged at ~18 times the normal data rate (!). I am very rarely on roaming data from what I've noticed currently, but this might be a deal killer for some people. FWIW, my current total cell/roaming data usage for last month was 809MB/3.1MB. This will of course vary depending on your coverage area; I'm in Jacksonville, FL with pretty good coverage generally.