Thanks for the pointer! I've just had a skim through it.
Initial thoughts: code is king. If it gets adopted, then that's what we have to deal with.
Personal opinion; the standard is .. not the way I'd like it to be. Neither for TZ nor leapsecond information. I dislike the idea of stashing this in a SRV record in DNS. I dislike the lack of authority on where the information comes from. A laptop moving from one network to another could be in contact with systems that provide TZ data from different sources, but legitimate from the standard, instead of a single source of internet-wide truth.
I furthermore dislike the complexity of the standard. The TZ data really doesn't need localization. This can be provided client side. Imagine a laptop talking to one TZ server not understanding the replies from a different one, due to localization [not entirely sure if this is correct, I might have skimmed too quickly].
Then we have the 'version' string in the replies that is sloppily defined. Why have it so general, instead of a simple .. timestamp in seconds since epoch?
There are lots of other nits and pieces I rather dislike - but also the entire idea that we should base it on HTTP and JSON. It also seems a bit too closely integrated with iCal from the get go.
To sum it up: I'm not a fan of the standard. But as I didn't put my money where my mouth is and created my own when I started becoming interested in this problem some ~10 years ago, I'll go "mergh. ok then" if it's adopted in general.