Ultimately this is the same basic console as we've had since launch. There's no slimming down, no funky color schemes or anything like that. It's a regular looking, black, heavy Xbox One console. But there are a few differences.
The first is the internal storage. It's the headline feature for this version of the console and represents the first time Microsoft has offered 1TB outside of the special edition Call of Duty console that launched in late 2014. It's a little more expensive than the 500GB version, as you'd expect, commanding a £50 premium in the UK. But you get double the storage, at least (or around double, when you take into account system files and such.) The big advantage here is that you're going to last longer before needing to hook up an external hard-drive, and for some of us, not having such a peripheral hanging around in our entertainment center is worth the extra cash.
And for what it's worth, the available space to use seems to be 780.8GB.
The second noticeable difference is that the 1TB console comes with a matte black finish on the top where the 500GB is glossy. It's down to personal taste as to which looks better, but we're fans of the matte look around here. Doesn't look as bad when it inevitably gets covered in dust, either.
The controller has been refined (see here for a closer look at that) with one of the major new features being the addition of a 3.5mm headset jack on the bottom. This is reflected by the new headset that comes bundled with the console, with Microsoft swapping the Chat Headset for a more conventional one with a 3.5mm connector. I'm not a fan, personally, but then it's less of a chore now to use something else.
All round Microsoft has a good package on its hands here. The question of whether you should get one or not is a little trickier. If you don't yet own an Xbox One, the not massive price bump over the 500GB version makes it probably worth getting, if for no other reason than to avoid having to plug in an external hard-drive quite as soon.
If you already have a console, the decision is trickier. If you can get a good price for your current console or you just really like the matte finish, then maybe. But you'll be able to get the new controller separately soon enough. It's a less compelling upgrade for people who already have an Xbox One.
And you'll have to spend a whole bunch of time reinstalling hundreds of GBs worth of games. Like I do. See you in a month.