Here's my unqualified review of this update:
The keyboard looks a bit chunky compared to the previous one which was just a thin slice + battery compartment, and I think it just looked better and more "Apple-y". Also the batteries lasted more like 6 months instead of just 1 month (according to Apple's site) while apparently taking up much less space. The less often you have to think about it running out of power the better.
The lack of backlight kind of sucks, it's really nice to work in almost complete darkness when you're working with photos. When you're typing, it doesn't matter much, but when you're using Photoshop shortcuts you depend a lot more on seeing the keys. Though I guess with the 1 month battery life, a backlight would have made things even worse.
The Magic Mouse to me always felt quite horrible to use. I love the touch scrolling and the way it looks, but the fact that you can't do a right click without lifting your index finger always bugged me. Gestures are limited and awkward on it, and on a Mac you kind of rely on gestures after a while. I do prefer Apple's trackpads, and only use a mouse for gaming, but the Magic Mouse sucks for gaming. Even a cheap Logitech works better for that. Apple never got mice right.
About USB-C: if Apple believes USB-C is so awesome that they could make a laptop that has no other ports than a single USB-C, then why aren't they doing everything they can to make people adopt it quickly? It sucks to buy a laptop that you can only ever use with expensive Apple adapters hanging out from the side. Then one day you forget your adapter and you can't even plug anything into it, what kind of laptop is that? Then by the time USB-C will be a common thing, your laptop will be obsolete so you never got a chance to enjoy its cool new "all-in-one port", it was just a pain in the ass all along. As long as there are new "regular USB" computers coming out, manufacturers are just going to ship most of their stuff with regular USB, which in turn will delay the adoption of USB-C. In a world where you can never have a computer that has up-to-date ports without the need for adapters for more than a few months, why not speed this painful process up? So far Apple still only has one computer that supports USB-C.
And it's nice and all to release new iMacs with faster processors, but the most noticeable way to make a computer faster is by putting an SSD in it. No one is going to notice a CPU that's 7% or whatever faster. But a boot time that goes from 40 seconds do 5 seconds is pretty cool, or launching Photoshop in 1 second instead of 5 is really handy when you do it all the time. Don't know about the Fusion Drive, but the 24 GB SSD in it sounds dangerously small. I don't know what AI algorithm can make up for that, when even a 10 minute iMovie project can be around 40 GB. I mean you won't even be able to work on anything in iMovie by benefiting from the SSD.
Weird update!